Dream Theater is pretty good as far as talent. Their songs are quite complex and thoughtfull (sometimes boring though). I dont think John is the only factor, cause all their members are some of the best of their kind. Key board, bass, and drums are all synchronized and makes for a very cool effect. Their singer is also one of the best metal vocalists right now.

Technically, Dream Theater is one of the most skillfull bands at this time. All their members are educated vastly in the music they play and that maybe why their music sometimes sounds overwellming, or just over done.