I'll be the first to admit that the movie is really cheesy in some places and that some of the dialogue is downright awful.
But that's not the point.
SPOILERS GALORE!!! 
<pseudo-soabox>
The point is this question: "Did the movie successfully tell the story that needed to be told?" Let's see:
1) Resolution of the Clone Wars *check*
2) Death of Count Dooku *check*
3) Death of General Grievous *check*
4) Revelation of Palpatine as Darth Sidious *check*
5) Anakin "converting" to the Dark Side *check*
6) Galaxy-wide Jedicide *check*
7) "Cleansing" of the Jedi Temple *check*
8) Birth of Luke and Leia *check*
9) Death of Padmé *check*
10) Obi-wan and Anakin duel to the bitter end *check*
11) Anakin severly wounded in duel with Obi-wan. This must somehow involve a river of lava (or so the books say) *check*
12) Rebirth of Anakin as Darth Vader in full scuba regalia *check*
13) Construction begins on the Death Star *check*
14) Luke and Leia split up and sent to Tatooine and Alderaan (respectively) *check*
15) Yoda and Obi-wan go into exile on Dagobah and Tatooine (respectively) *check*
16) Reformation of the Republic into the Empire *check*
All of those took place. Therefore the story that needed to be told WAS told and Revenge of the Sith therefore qualifies as a "good movie". It's a completely different subject as to whether you thought the execution of the movie was good.
</pseudo-soabox>
Dave