Things I liked. . . . .
Hrm. Ian McDairmid earns his pay and then some - the bit with him talking about his old master was actually chilling. Until he whips out the ol' lightsaber and makes with the kung-fu, Palpatine is an impressively sinister character. Even his "Are you threatening me, Master Jedi" line is impressive due to excellent acting.
The early bits of the Republican Schism are interesting, with both Palpatine and the Jedi trying to use Annakin against each other. I'm a sucker for "conflicting loyalties" plots, and this one was good at the outset.
Annakin's character finally, finally comes out in a realistic way. Hayden Christiansen, wooden line readings aside, manages to convey a young man who knows he's done bad things, knows he's teetering on the brink of true evil, and is desperately casting about for some way back.
The closing duel between Annakin and Obi-Wan is top-notch. While not as choreographically stunning as the closing duel in Phantom, it's much more moving since it's between two evenly-matched fighters, old friends who now hate each other intensely. You can almost feel how much each wants to hurt the other while watching it.