Brothers and Sisters is the biggest disappointment this year. It is just so over-the-top all the time -- worse than Falcon Crest ever was.
Private Practice was tough to watch, too, until the cross-over episodes with Grey's Anatomy, which, although it wasn't really "bad" this year, was definitely no where near as good as it was two years ago.
We've gone back and forth with both Life and Criminal Minds; we're currently back watching Life, after dropping it for a while, but we've dropped Criminal Minds, probably for good, now.
Numb3rs is getting a little repetitive, too.
By contrast, a bunch of shows are as good, if not better, than they've ever been, including Lost, Battlestar Galactica, Heroes, NCIS, Psych, and The Unit.