These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Lucas may have retconned the George W. Bush reference since the film was made during the 2004 elections but released afterwards. Lucas only denied that it was anti-Bush after President Obama was elected, who Lucas supports but who has many similar policies. In particular, Anakin's phrase "You're either with me... or you're my enemy." is a reference to (one formulation of) the Bush Doctrine that countries that support terrorist groups are treated as if the terrorists are acting on their behalf. (It's also a re-phrasing of the classic liberal political saying, "You're either part of the solution, or you're part of the problem.")
It's also been noted that Palpatine's rise to power has more in common with that of Caesar Augustus, Napoleon Bonaparte, or Adolf Hitler.
Broken Base: The worst out of all of them. The main issue being if Anakin got better or worse as a character.
Complete Monster: Palpatine. Add-on materials including the novelization reveal he was angry at Anakin for losing to Obi-Wan and considered leaving him for dead since he was crippled both physically and in his strength with the Force. The only thing that convinced him otherwise was that Anakin would still be powerful even in this state. On the other hand, in the movie he seems only to be impressed that he was alive, and isn't angry at all. He also did much the same thing with General Grievous— manipulating him into being horrifically crippled so that he could be re-built into a super-cyborg monster.
Contested Prequel: Like the other two prequels, though leaning more towards the positive end of the spectrum.
Critical Dissonance: Gets enough flak from fans that its Rotten Tomatoes rating of 80% might surprise some people.
Many critics erred on the side of trashing the original trilogy, and modern critics would rather err on the side of what would have seemed to have been a sure thing.
Fight Scene Failure: The Palpatine/Windu fight looks rather pathetic, due largely to Lucas' insistence that the elderly Ian McDiarmid do it himself instead of using a stunt double and digital face like they did for the Dooku/Yoda fight in Attack of the Clones.
Somewhat josssed in the sense they did use a stunt double for Ian Mcdiarmid. They had to use him in the close up and mid shots.
Harsher in Hindsight: The already horrific multiple-murders of Order 66. If you've watched Star Wars: The Clone Wars, every Jedi they show getting murdered has gotten screentime and lines, which is more than you can say for the movies. They're that much more alive, and their deaths are that much worse.
He Really Can Act: For a few minutes when he has no lines as he begins the massacre of the Jedi Temple, Hayden Christensen is genuinely scary looking as a dark-sided Anakin, now Darth Vader. While this is also a polarizing performance, many fans who don't hate the film point out how the way Hayden Christensen acts is a lot more appropriate than in the previous film, where it was more narmy.
While many who don't hate Hayden himself point out that Lucas' writing and direction in Aot C didn't give him a lot to work with, either...
He's Just Hiding: Was claimed Mace Windu and Aayla Secura, even though they're both killed onscreen. Mace's survival is at least somewhat plausible. He loses his hand, gets zapped by lightning, and tossed from a significant height, all of which Jedi are shown to be able to survive throughout the saga (although never all at once.) Secura however, gets shot in the back by at least a dozen troops at near point-blank range, and her body continues to be shot as the camera pans out.
Much of the reason Anakin loses trust in the Jedi and eventually betrays them is due to them not trusting him, thus giving him good reason to do the same. In the end, Anakin's betrayal of the Jedi was as much them pushing him away as him turning his back on them.
Also, Anakin's (and the rest of the Jedi's) failure to spot the obvious - that Palpatine was the Sith Lord. He was almost amazingly athletic during the escape from the Invisible Hand, especially for an aging politician. Then there was his creepy storytelling at the opera house. Finally you have the simple and obvious fact that he was increasingly dictatorial. It was really kind of glaring.
Magnificent Bastard: Palpatine. He plays every single character in the movie like a fiddle and becomes dictator of the galaxy by the end of the second act, and by the end of the movie all of his potential enemies are either dead, on the run or on his side. Granted, at least part of this is because some of those enemies are not always the brightest folk, but they suspected that something was wrong with him being in power so long and thought at the very least that the Sith might be controlling him, and he still covers his tracks until its too late for them.
On the flip side, it can be argued that Palpatine succeed not because he was just that good of a manipulator, but because the people he was up against were complete idiots that failed to see his obvious machinations until it was too late.
Memetic Mutation: Vader's "NOOOOOOOOOOOOOOOO!!!" has since been used as a way (mostly in jest) to show great disapproval over things on forums and message boards.
The NO part also spawned a different famous meme thanks to a cheap chinese bootleg of the movie having horribly translated subtitles in english. During the scene the "no" was translated as "Do not want!" which quickly became a reaction comment towards unwanted things or gross images.
"You underestimate my power!!!"
"Only a Sith deals in absolutes."
"You were the chosen one!", usually in rage comics to show betrayal but full variations of the quotation have been made◊.
When Anakin has Count Dooku at his mercy, Palpatine implores Anakin to kill him in a very forceful way, specifically using the phrase "DO IT!" fiercely. After Game Grumps made fun of the scene (showcased throughthesevideos), it's hard for one to take it seriously.
"Anakin... has killed... younglings." Child murder is horrific in and of itself, but the word "younglings" either spoils the mood or makes it feel less like the real world and more like Star Wars.
Natalie Portman is a good actor, but even she can't make a clumsy line for her character's anguish, "Anakin, you're breaking my heart." sound anything but stupid.
Nightmare Fuel: Anakin/Vader's transformation from man into human-machine hybrid. Word of God has stated that he was not on any anesthetic, so he was awake and in horrible pain the whole time he was being placed in the suit.
Plus Chewbacca, who's also played by the same actor.
Surprisingly Improved Sequel: Most fans agree that Revenge of the Sith is the best of the prequel trilogy. Some fans even consider it to be on the same level as The Empire Strikes Back in terms of quality.