I do use Audyssey on my Denon 2309 as well as the dynamic volume (loudness leveler) and multiEQ for both commercials and because my kids go to bed early. Its defeateble but should be an option on every receiver or pre/pro. Its actually a limiting factor on some of the botique brand receiver and pre/pros I'm looking at upgrading to (Emotiva, Rotel, NAD).
I also don't understand these reviewers who state "I turned on X movie mode, it worked and sounded great and made the bass tighter, treble airier and music more cohesive...so, of course I turned it off for the rest of the review...what?!? The idea is to hear the receiver at its best...that you want to hear the receiver at is uncalibrated state is bogus (especially when its designed to calibrate itself). That's just like buying a projector or TV and watching it on DYNAMIC store mode for the entire review (which has not been done in the recorded history of TV reviewing I think). Further, maybe you should compare an Audyssey receiver against a non-Audyssey receiver...if the Audyssey receiver spanks the other one maybe the botique manufacturer will take the cue and upgrade the receiver in the future.
For those stating they are purists and anything but passthrough changes the sound, sorry, but unless you listen in a recording/mixing studio the same size with the same treatments you are already changing the sound.
Just listen to it in whatever way is most enjoyable to you...