Well, I think whenever Annakin is on screen in dramatic parts, it feels quite poor and drags by his mopey teenager persona, but there were two dramatic scenes I thought were decent. The first, the death-scene of Shmi Skywalker, was actually very good, and the second, where Annakin reveals what he did to the Sand People to Padme, was reasonable. The action parts are mostly fine as long as Annakin isn’t speaking.
On the other hand, I very much enjoyed the scenes where McGregor was present and not encumbered by the presence of Annie, as well as any scenes with Yoda, Mace Windu and Count Dooku. Particularly enjoyable parts were the fight between Obi-Wan and Django Fett, and the whole last act in fact (especially the fantastic fight between Dooku and Yoda).
Also good was Jar Jar was in this one much less than I remembered, thankfully.
I think, and I need to rewatch Revenge of the Sith to be sure, this is my favourite among the main prequel movies.