Greivous was lame, especially after how built up he was in Clone Wars. Darth Vader/Frankenstein scream=absolutely ridiculous. THAT should have been left on the cutting room floor. Not the Darth Vader I know from the OOT.
Although the Mace Windu/Palpatine duel was done pretty well overall, there was just something weird about that scene that bugged me. Maybe it was Mace's death, which wasn't very noble. Christ, he was fried for a good 10 seconds by Palp's force lighting and thrown out the window! It would have been better if Anakin had just cut off his hand or killed him outright and have him fall out the window. The lightning (and Palpatine's associated laughter/screaming) was just too much. I think I was just bothered overall with how inept the Jedi seem in the entire PT (except for Yoda). Although I guess part of their downfall was because they had indeed grown too arrogant (as Yoda mentions in AOTC).
Yes, there were some (very) cheesy moments and dialogue ("Not if anything to say about it have I") but it was definitely a vast improvement over the previous 2 films. I'd agree with JediSage and say that it was as good as, but not better than, ROTJ (I was young enough to like the Ewoks and really enjoy ROTJ when it came out in '83). None of the prequel films match the OOT IMO, but ROTS comes close! I'm looking forward to seeing it again digitally projected at the Metreon here in San Francisco (in a few weeks after the crowds dissapate).