There is a rule you can apply to most movie trilogies: The second movie in a trilogy is either the best or the worst, never in between. You can debate whether this holds up for other trilogies, but for the Star Wars prequels, it's true: Episode II is clearly the worst of them.
In order to further the plot established by the original trilogy and “The Phantom Menace,” there are several key plot points that need to occur. First, the Dark Side must strengthen its position and pave the way for the creation of the Empire. Second, Anakin must fall in love with Padme and begin his path toward the Dark Side and his eventual transformation into Darth Vader. Star Wars has entertained us before with Han and Leia’s love story and Luke's journey to become a Jedi and reject the Dark Side. These are powerful plots, when done correctly. Episode II should be a good movie. The problem with the “Attack of the Clones” is that none of it is done correctly.
We can start with the love story. How Padme ever falls for Anakin is baffling. He shows incredible ignorance concerning politics – her job and seemingly her main interest – going so far as to say that a dictatorship would work better than the Republic. On Tatooine, he confesses to killing an entire tribe of sand people, including women and children. “They’re animals, and I slaughtered them like animals!” he screams in anguish. Yet Padme still wants to be with him. For a senator committed to democracy, this seems like a stretch.

Who wouldn't fall in love with this guy? He can levitate a pear!
The ridiculousness of the love story is compounded by the fact that Natalie Portman and Hayden Christensen have absolutely no chemistry. When Anakin makes several comments upon meeting Padme again, she rebuffs him, saying he makes her uncomfortable. This is the most believable piece of dialog exchanged between the two. Nothing he does afterward ever redeems these awkward moments.
Even when not wooing Portman, the rest of Christensen’s performance is whiny and childish. There is no sense of camaraderie between him and Obi-Wan, and he seems perpetually ungrateful towards his mentor. At some point, a rift does need to be formed, but there is never a sense that they were ever good friends in the first place. The audience can feel no sympathy for Anakin during the difficult times of the film because he is so immature and self-absorbed. I never sense that he loves anyone other than himself. Even the supposed anguish he feels over the death of his mother seems selfish and petty.
While the romance and Christensen's acting are massive flaws, the arc of the Dark Side seems more like a missed opportunity. Some of the best parts of both Episodes I and III involve Sidious/Palpatine’s manipulations and intrigue, but the best we get here is a brief, seemingly ineffective effort to breed discontent in Anakin against the Jedi, as well as the poorly delivered effort to get Jar-Jar to propose a bill to raise the clone army. The Jedi should be oblivious to these maneuvers, but the audience does not need to be.
The rest of the movie is the final land battle between the clone army and the droids, culminating with the fight between Dooku, Anakin, Obi-Wan, and Yoda. This final scene is irritating. Anakin, as usual, is uncontrolled and whiny. Yoda, who should be the wise Jedi, not the warrior, is seen fighting with a lightsaber. The scene feels like a significant violation of the character while also committing a far more mundane crime: it just looks lame.

Whatever your thoughts on Episode II's arena fight, at least it introduced us to Kit Fisto.
There are some bright spots. Half of the movie contains Obi-Wan’s journey to find the source behind the assassination attempts against Padme. The various confrontations between Obi-Wan and Jango are pretty good; both the fight on the platform and in the asteroid field are entertaining and creative. I especially enjoy the sound effect for Jango's sonic charges Jango. Additionally, watching all of the Jedi in the arena is fun, albeit brief. Dooku is somewhat interesting as an evil mastermind, but he ranks far behind Sidious's high points.
While the kernel of its conception is good, “Attack of the Clones” is a bad movie. There are a few entertaining moments and a decent start of a plot, but the film is plagued by bad acting, wooden dialogue and a dearth of Palpatine's Dark Side machinations. Ultimately, the movie fails to be as affecting as it should be.