After receiving my Windows copy of Adobe's Acrobat Professional yesterday and my Macintosh version today, I'm ready to give some initial reactions to the versions.
So far, so great. It's been a long time coming on the OS X side, and because of the annoyance of missing features in "real" Acrobat 5 under OS X, I won't say it was worth the wait, but the new version is really nice.
The UI is a bit XP'ish in terms of the large icons and so forth, but the functionality is there and the speed appears to be better for most things.
Adobe Catalog is now available inside of the program, although the format of the index files appears to have changed. Recatalogging existing file sets was simple and straightforward (although it will require that the new index be read with version 6 of Adobe Reader or Acrobat.
Lots of support for signing, editing, etc. and a lot of new preference panes.
Installation of the upgrade package was easy. On the Mac, it's a drag-and-drop install and contains a self-installer (like we saw in Microsoft Office X) to add in whatever special pieces are necessary. The installer recognized my existing 5.x version and took my upgrade key just fine.
Unless you hear from me again on this topic, you can assume that it is working well.