So, how many of you are going to switch?

I added CS5, or AA4 the minute it became available.  I use it 80% of the time, but still have to go back to AA3 for the features they left out of it.

I haven't messed around with the dither to see if it has improved, because I am very happy with MBIT+ available in other vendors' software.

Not to CS5.5, but I expect to upgrade to CS6. Even without the discriminatory pricing policy here in Oz I'd be waiting for the return of the misplaced features.

FWIW I'm finding the combination of Audition for editing & Reaper for multitracking to be close to ideal for my purposes (which gets me back to using AA for the original reason I started with Cool Edit in 1995).

which is more or less the approach I'm pursuing.  Live shows/field recording I tend to use some variation on an HD recorder ( Alesis discontinuing ADAT HD makes the next upgrade there to something like the JoeCo Black box . . . significantly more expensive and places Audition upgrades even further on a back burner)

I am still pretty OK with Reaper for tracking (and unfortunately end up doing way more tracking in ProTools then I'd prefer).  And still employ Audition almost daily in some capacity.  But so far I see nothing (trying to balance things gained vs things lost) in CS5.5 that suggests any competitive advantage.  That it is essentially the 'Mac' version does not interest me in the slightest.  Over a period of about 18 mnths, initiated by my continuing disappointment in the direction MS is moving, with regard to Audio/Vid production I explored Mac as future hardware platform.  And I have a number of acquaintances in tech fields who are, after a lifetime with Wintel seriously enamored with newest Macs.  But I still don't get it, neither from a Hardware nor Software perspective.  Hardware remains a sort of no brainer in terms of cost and flexibility (that with Apple one still pays way too much for the supposed sex appeal) but I was very disappointed  that in the latest production OS the supposed Unix core is seriously compromised (i.e. not Unix like) for anyone attempting to build a local intranet (networking a handful of machines for any sort of 'production').

Admittedly MS is not much better but it is a case of devil you know. 

So?  Tailoring Audition to work with Mac OS is no marketing point for me.  . . the opposite in fact.

If I live long enough I will probably be forced to upgrade AA at some point, but doubt that it will be in 2012.

I am a home user of AA3 and it was my third version purchase starting with AA1.  I've read these threads with interest as I consider whether to  upgrade.  I know that some on this board would like to see the MIDI dissappear altogether, but one of the primary purposes I use AA3 for is to sinc up my midi backing tracks I created in other products, convert them to digital recordings and then record in the vocals, and then mix and master the whole thing.  AA3 gave me great control over that process and good access to all my VST instruments and effects.   If AA4 does not have MIDI, then there is no reason for someone like me to upgrade, although the improved speed would be nice.  Even if they add into AA6 much of what they left out from AA3, by then the upgrade from AA3 will be even more expensive, and will still be an initial release of new, untested features, so I will probably just start looking for something else now rather than wait any longer for AA to become what I need to be.

Considering how you are using it, I recommend not purchasing (I hesitate to call it an upgrade).  I purchased it and really dislike it so far. 

I read a few forums and a number of people enjoy working with Reaper.  You might want to give it a look.

Considering how you are using it, I recommend not purchasing (I hesitate to call it an upgrade).  I purchased it and really dislike it so far. 

Can you tell me what it is specifically that you don't like? The more ammunition I can gather, the better...

Considering how you are using it, I recommend not purchasing (I hesitate to call it an upgrade).  I purchased it and really dislike it so far. 

Can you tell me what it is specifically that you don't like? The more ammunition I can gather, the better...

Since you've asked...
I spent the last 5 days working with it just to put it through its paces and make sure there weren't things I was just missing or maybe just complaining about because they were somehow a bit different. 
I work a lot in Multitrack and they've really made the Multitrack section more like the clunky MT section of their video editors (I have owned Adobe CS3 Production Premium for over four years).
In Multitrack I hate...
...the absence of a toolbar.
... the lack of ability to select many clips at once and group them in one click. (The new way, selecting each clip and then sliding, is awful and slow.)
... the way the program reacts when moving clips.  It is now very slow and awkward to line up something exactly when matching.  I don't need a box to pop up when I move a clip!  When I've moved a clip and stopped moving it, that is where I want it!
... the new way to call up an effects rack.  I don't want to be forced to do a couple of keystrokes now or some menu clicking to bring up a track's effects rack.  Double-clicking on the effects rack of your chosen track was a very simple and quick way to access the effects rack.  It wasn't broken but they decided to break it.
... the fact that, once an effects rack is chosen, the plug-ins GUI in the effects rack does NOT come up with it.  One must click on the chosen plug-in and then a separate window pops up with the plug-in, thus cluttering up the screen.  I end up moving the windows around so I can see both the plug-in and effects rack at the same time in order to see the I/O meters of the effects rack AND any metering on the plug-in.  This change has made the process slow.  (Sorry, Adobe, but I like to set good gain structure, unlike many video editors whose work I've had the misfortune to hear.)
... the lack of ability to zoom in vertically using the scroll bar.  It's now click, click, click instead of simply grabbing the top or bottom of the scroll bar and stretching or shrinking it, thus zooming vertically.  This change is utter nonsense and slows down workflow (hmm, I'm sensing a theme).
... the new, see-through faders that are the same color as the background upon which they rest.  This makes them harder to see compared AA 3.0.1, or any other virtual or actual mixer I've EVER used!  The faders don't need to ever be slightly transparent - they are only good for getting to a certain range of a number, and any incremental changes are usually typed in by me anyway.  The worst part of this change in faders is that they now change brightness along with the background, thus ALWAYS making them the same color as the background - and that is truly stupid.
... the absence of color to the Mute, Solo and Record buttons when not engaged.  They've made them all look the same with the exception of a letter.  Once again, truly stupid.
... the new GUI that has made divisions between mixer channels much less distinct, regardless of color scheme and brightness chosen.  It appears as one big mixer mess.
... that there is NO MORE hybrid too, but instead the Time Selection tool acts most closely like the hybrid. 

In general, I hate...
... the new GUI.  It has made everything really uniformly utilitarian and ugly.  There is much less distinction between windows, regardless of scheme or brightness.
... the fact that there is no more Multitrack View without a Multitrack session being open or creating a new session before it will open.  Having to create a session, with parameters, before Premiere Pro would open was a default in CS3 and I hated that too.

I have not been doing much editing in the program yet, so I don't have many specifics on my dislikes of the editing section. 
I understand that this program has been molded to integrate more easily with the other Adobe products, but in doing so they've lessened Audition.  Rather than taking much of the best of that program and integrating those features into the other programs they've instead chiseled away at Audition by taking away features and functionality that made it a great program. 
I'll still be attempting to tame Audition CS5.5 but it will still just be viewed by me as an experiment to try rather than as a useful tool.  I'll be sticking with AA3.0.1 for the foreseeable future. 

Thank you, Eric. Feedback will be passed...

... the new, see-through faders that are the same color as the background upon which they rest.  This makes them harder to see compared AA 3.0.1, or any other virtual or actual mixer I've EVER used!  The faders don't need to ever been slightly transparent - they are only good for getting to a certain range of a number, and any incremental changes are usually typed in by me anyway.  The worst part of this change in faders is that they now change brightness along with the background, thus ALWAYS making them the same color as the background - and that is truly stupid.
... the absence of color to the Mute, Solo and Record buttons when not engaged.  They've made them all look the same with the exception of a letter.  Once again, truly stupid.
... the new GUI that has made divisions between mixer channels much less distinct, regardless of color scheme and brightness chosen.  It appears as one big mixer mess.

In general, I hate...
... the new GUI.  It has made everything really uniformly utilitarian and ugly.  There is much less distinction between windows, regardless of scheme or brightness.

Yep you can have your channel strip any colour you want as long as its gray and indistinguishable from any other channel strip
I can't estimate the reverse workflows this has caused me on a multiscreen setup.

Thank you, Eric. Feedback will be passed...

Thanks for asking.  Your question made me pay more attention to my workflow on CS5.5 vs. 3.0.1. 

Yep you can have your channel strip any colour you want as long as its gray and indistinguishable from any other channel strip
I can't estimate the reverse workflows this has caused me on a multiscreen setup.

It is quite frustrating and, in my opinion, it's a very bad call by the Adobe people.  They've really taken their programs backwards with these new GUI setups.  For some reason they change the appearance of their programs with every new version.  One would think that a company that employs many graphic designers would actually listen to some of them and decide to make their products unique to view and use, but instead they give us something that appears to have the GUI design modeled after an Eastern Bloc housing complex circa the 1960s.