Warning - spoilers!
My first impression of the movie is that it is one of the best, probably falling just after The Empire Strikes Back. Yes, some of the dialog is poor but that is confined to maybe a half dozen lines. To me, the most important part is the middle act. To me this is what makes or breaks a Star Wars movie. I don't like the middle acts in Return of the Jedi and Phantom Menace. The Ewoks were cute the first time around but they turn cloying on repeated viewings and I didn't care much for the pod race in Phantom the first time I saw it.
Now, in the original Star Wars, the middle act is where things really get going. We have the three principals finally meeting and Obi Wan getting killed. There's not a slow moment in it - those were all in the first act. In The Empire Strikes Back we meet Yoda, who remains interesting four movies later, we see Luke's Jedi training, and we see Han and Leia escaping to the Cloud City.
I will add that I like the middle act in Attack of the Clones which means I rank it higher than most people.
In Revenge of the Sith, the middle act is the corruption of Anakin. It works. The seeds were planted in the second movie and we knew it.
Lucas turns a science fiction cliche on its ear. All too often love is portrayed as humanity's saving grace. In RotS it is love that turns Anakin to the dark side.
The Jedi are largely inspired by Chinese monks. The original movie was written while Kung Fu was a top-rated TV show. Like the monks, the Jedi are a martial order who use exotic weapons. They are supposed to suppress strong emotions. When you can strangle someone at a distance, this becomes a necessity.
There is an implied feedback loop where strong emotions trigger a response in the Force making you more powerful but corrupting you. This could have been explained better. In AotC, Anakin kills a tribe of Sand People then feels guilty for letting his emotions get the better of him. Padme doesn't help things by telling him that it is ok to feel. It is for most people but not the Jedi.
Jedi are supposed to go through life like the Chinese monks, few possessions and no emotional attachments. Yoda tries to explain this to Anakin but by then it is too late and Yoda's warnings come across as uncaring.
Here's where we get to classical tragedy. The basic of a tragedy is a character flaw in the hero. In Anakin's case it is that he loves too often and too strongly. We were warned back in Phantom Menace that this would cause trouble. The love for others turned to fear which turned to hate, etc.
There is also the issue of prophecy. Anakin tries to alter the future but in doing so he sets in motion the actions that kill Padme. If he had left things alone it would have been a false vision. In attempting to change the future he gave Palpatine the opening he needed.
There is a different aspect to this that is interesting. While Anakin feels himself worthy of being a Jedi master, he also knows that he is a failed Jedi. He killed the tribe of Sand People. He has a wife. When he had Count Dooku at his mercy he kills him even though this is not the Jedi way.
Anakin judges the other Jedi by a higher standard than himself. He might fall but they should not. The tipping point is when Mace Windu prepares to kill an unarmed Palpatine. Even though he killed Dooku under similar circumstances, Anakin is horrified to see Windu kill Palpatine. Of course, had Anakin been there a couple of minutes earlier when Palpatine killed three Jedi masters, Anakin might have felt differently and killed Palpatine himself. Timing is always important in tragedy, also.
There were a few things that could have been done better. As the Jedi went to arrest Palpatine I was wondering if the separatists, the bad guys in Phantom Menace and Attack of the Clones, were somehow going to turn into the good guys. As it turned out, the separatists were wiped out by Anakin. In a cut scene, several senators including Padme and Bale Organa, sow the seeds for the rebellion. For that matter, Organa suddenly goes from being an extra to a major character. That transition was abrupt.
Also, I was disappointed that Vader was in the black armor so late in the movie. I was hoping to see more of the classic Vader. Once revived his part is limited to looking at the Death Star being constructed.
And why does it take 20 years to build a Death Star?
It doesn't really matter but Yoda mentions that the prophecy about a chosen one killing the Sith and restoring balance to the Force might be wrong. Did someone get it totally backwards or was it referring to Anakin's son instead?
One lingering question - what killed Padme? The medical droid said that she simply lost the will to live. I don't think that this is actually fatal. Palpatine told Vader that he killed Padme. Given Vader's ability to kill at a distance and the fact that he had already choked her once, this might be true. Either way, Anakin killed her. Its just that one way was more direct that the other.
The movie ended on one hell of a cliffhanger. Except it wasn't because the next three installments have already been made.