The story continues of Anakin Skywalker turning into Darth Vader; only about ten years later, flashing forward so far that they had to get a new actor for Anakin--and yet didn't have to for anyone else, not even Padme. And now we get to watch one of the biggest examples I've ever seen of what could've been, was not.
In this film, we end up getting a brand new antagonist to replace Darth Maul--this one the much older Count Dooku (Christopher Lee), who's basically threatening to take over. And with about four actual Jedi (Anakin, Obi-Wan, Yoda and Mace Windu), the Republic wants to get an army to help them fight back--but they keep on facing opposition, including Padme--one of the voters on the situation--having repeated attempts on her life. Thus leaving Anakin to be Padme's guard, while Obi-Wan goes to deal with some unbelievably cartoonish aliens (seriously, what were the guys in the creative department thinking?) and dig up the scoop on the clone army.
Attack of the Clones is, as a whole, more action-packed than its predecessor, which certainly helps it out. None of the sequences reach the level of the duel at the end of the Phantom Menace, but we're given more in quantity this time to keep us from falling asleep. The last 30-40 minutes are quite an action-packed climax that help make it worth the ride. It also helps that Jar-Jar Binks only gets about ten minutes of screen time in this film.
However, there's a lot wrong with this film. Part of it is the direction; much of the film feels rather sloppy. The script is quite thin, which makes me feel sorry for the film's mostly-excellent cast. As mentioned earlier, the aliens they come up with are just ridiculous. The worst part, though, is Hayden Christensen as Anakin. In this film, this guy cannot act to save his life. The script may not have been helping much, but either way, he's more annoying than anything. It's a shame too, because things get interesting as his hidden anger shows up, and if there had been a better actor, his feelings could've been portrayed far better; instead, he just sounds like a spoiled bratty 12-year-old.
That's the perhaps biggest example of something about this film that could've been far better, but just wasn't. And sadly, there were many other little things that they could've done/not done that would've helped immensely. For example, the battle droids are all but gone, and when they do show up, there's very little of the comic relief they had in the first film. Also, there's an incredibly long "action" sequence involving Anakin, Padme, 3PO and R2 being stuck in a factory that is ultimately more boring than anything. Another thing of note is that, near the end, an injured Obi-Wan throws Anakin a second lightsaber to help him fight Dooku, but that second lightsaber is quickly destroyed. Think of how awesome it would have been if we had an extended fight with Dooku vs. Anakin with two lightsabers. (Or, even better, we could've had Anakin with two lightsabers vs. Darth Maul... but we know why that couldn't happen.)
It's little things like this that kind of bring the film down. Yes, it's entertaining and there are some funny bits, and the backstory is still interesting, but Attack of the Clones is tortured by poor direction, poor dialogue, and horrific acting from Hayden Christensen. The biggest Star Wars fans should probably be entertained still, and there are indeed some bits that make it worth a view, but ultimately, Attack of the Clones is an attempt at a possibly good film wasted.
Postscript: I'm not quite sure why this film is called "Attack of the Clones." Aside from the training facility scene, we don't even see them until the last 25 minutes--and they don't really "attack" anything (they defend the Jedi), and they're not enemies, which is sort of the impression one kind of gets from a title like that. If you had to mention the clones, maybe Rise of the Clones? I dunno. Whatever.