For me, TPM was a let-down - initially. Repeated viewings seemed to improve the experience, but it still seemed as if something was wrong.....
And then, one day, I realized that I had been watching the movies from the perspective of the original trilogy, and that wasn't going to work. The original trilogy was set in a "dark time for the galaxy", where the Emperor ruled absolutely, the Jedi were non-existent, and no one had the courage or the strength to rise up against the Empire. No one, that is, until that fateful day when a Corellian smuggler took on a charter consisting of an old man, a farmboy, and their two droids....
The Prequels, on the other hand, depict a universe that, while on the decline, is still a much happier place than it would be in the future. Slavery is virtually non-existent (except in the Outer Rim territories), and non-humans had as much freedom. The Jedi were a force (no pun intended) for peace and justice throughout the galaxy, and were generally held in high regard (unless you were a criminal, that is). Sadly, the corruption of the government only hastened the Republic's decline. Things were looking up when a greatly respected senator form Naboo was elected Chancellor.........Looking up, that is, until a headstrong Jedi Master and his Padawan found a young boy who seemed to possess tremendous force-potential, and took him to be tested and eventually trained at the Jedi Temple.