The only time I noticed Anakin's theme was in the closing credits, and even then, it's very brief. The Imperial March however, does make an appearance in it's full form. It isn't a transition from Anakin's theme, and from the tone of it, it sounds like it was scored against something "imperial" happening on screen, rather Anakin turning to the dark side. If Anakin's theme is expanded or modifed, it's not on this release of the score.
I don't like that they're using the imperial march in this film, given that A New Hope didn't have it at all. I'm also bothered by rumors that Williams is going to rescore A New Hope, so it matches the other movies thematically, being released as an ultimate edition. The prequels and their scores should have been designed around the existing three movies, rather than making modifications later so everything matches.
> I remember from reading the review of the Episode 1 soundtrack, about the
> couple of chords used in 'Anakin's Theme' which were from The Imperial
> Christian said something like how he couldn't wait to see how that cue
> would be expanded in the next film (this one) to become more and more