Hmm... I agree Mace Windu's death needed more work, as did Christopher Lee's (but maybe he was fortunate to get it early on). First he practically wins by using his lightsaber to rebound Sidious's lightning back at him, turning him into the frog faced fiend we remember from ROTJ, then Anakin arrives, slices his hand off (what is it with George Lucas and cutting off hands?) and this buys Sidious enough time to fry him and send him hurtling to his death. Dying after an exhausting duel with Darth Vader would have been a better end to Mace.
The opening crawl starting with "War!" I think that might be the weakest crawl of all the films.
I actually don't mind the Frankenstein "NO!" when Vader gets off the morgue slab. What I hate is how small he looks. Why oh why did George Lucas let Hayden Christensen let wear the Vader suit? Why couldn't he just say no to punk? Standing in at a lanky 6'1", Hayden is too small to be a visually effective Vader. Stand Hayden next to someone like Samuel L. Jackson or Liam Neeson, who are like 6'3" and 6'4" respectively and probably outweigh Hayden by about 30-40 lbs, and you won't deny he looks like an ant compared to Jackson and Neeson. Where's David Prowse when you need him? For that matter, where's Kane Hodder, Ken Kirzinger and/or Daniel Cudmore?
This isn't so much a thing I hated as just a little footnote - in the opening, Ewan McGregor sounded a lot like C-3P0.
There was a little more love between Annie & Paddy, but not quite enough to make me believe that he turned to the Dark Side for her. Padme dying of grief was a bad cop out.
Why wasn't Obi-Wan in the last frame looking out silently at the twin suns with Uncle Owen & Aunt Beru? Not hate, just curious. Given that he's more or less the hero of the film you'd think he could have gotten in one last look of regret. To be honest, I think the girl they picked to play the young Aunt Beru looks more like Carrie Fisher than Natalie Portman does, but hey, I might be crazy. They could have spent more time trying to establish a relationship between Anakin, Owen and Beru.
Another thing that's more of a nitpick note than hate was the climax - not only did it remind me of Lord of the Rings: Return of the King, it reminded me of Star Trek 3: The Search for Spock. I half expected Anakin to cling to a cliff, trying to pull Obi-Wan down with him, with Obi-Wan kicking him in the face shouting "I... have had... enough of... YOU!" But I guess GL was going for a Dantes Inferno type thing, battling it out at the gates/pit of Hell/Underworld.
The Jedi got killed too easily by the clones.
Those damn anorexic daffy duck robots! And Jar Jar... no dialogue fortunately, but why did he have to even appear?
Obi-Wan letting Anakin melt... sure it's fun to watch him suffer after all that stilted whining, but wouldn't the humane thing for Obi-Wan to do be to just lop Anakin's head off and put him out of his misery? I know that would rob us of the old films, but it seemed a bit insensitive on Obi-Wan's part.
Still, it was better than the first two prequels.