John Williams is one of my favorite composers, but I must say he disappointed me on this one. When I got the CD, I expected to hear "The Imperial March" in all its full-blown glory at least two or three times; in fact, I was seriously hoping for it. Instead, it is only played a few times and they are nowhere near as exciting as the versions played at the end of Attack of the Clones and in the original trilogy. Also, the music all sounds the same. Track 6, "Palpatine's Teachings" is five minutes of continous, one note chanting. The end credits, however, were the album's saving grace from eBay. They reprise some Original Trilogy music (Leia, Throne Room) along with Battle of the Heroes (which, though not as good as Duel of the Fates, is one of the CD's better songs).
The reason that you don't hear the "Droid Invasion Theme" and "Duel of the Fates" on this CD is that they were recycled from past movies. Oh yes, they were used repeatedly in this film, but as Williams couldn't be bothered to write an original arrangement of them, he simply grabbed up some old recordings from Phantom Menace and Attack of the Clones and stuffed 'em on the tape. But, he's made so many good scores for us, he can be forgiven this error.