As usual, someone with a more eloquent turn of phrase than I have (Ted Padova) has written a darn good review of some new Acrobat 9 features. If I were you, I'd check out the following link
By the way, here's the man in question....
Thanks to Ted for all his work.
But don't think this great summary will prevent me from having my own occasional rant about a great Acrobat feature here and there, stay tuned dear reader, stay tuned to this channel.