The music for "Star Wars" (1977) and for ESB are brilliant, original, and alot of fun to listen to. Return of the Jedi is still good, but includes some some earlier music just played in a slightly different fashion, and themes that I just don't find as interesting for repeated listening.
The PT seems to have very few noteworthy or memorable themes. ROTS seems a bit more exciting, but it's basically because many of the themes from the OT are being used.
Even the playing of the opening theme seems to be more and more muted and less detailed. In the PT the theme seems to sound more like ROTJ. I had hoped that Williams would use some variation to make the themes for the PT sound more like an earlier version of the one used in Star Wars (1977).