Piranha is either the finest schlock movie ever made, or a representation of everything that is wrong with America. It's hard to put your finger on the fine distinction, but the film celebrates the nudity and visceral gore that schlock films live on, and everyone's take on it could swing either way.
Good thing, then, that it's directed by Alexandre Aja. The man knows how to make movies, no question about it. He has an instinctive knowledge of pacing, mood and tone, which elevates this film from regular schlock flicks. At 80 minutes, the movie has been finely tuned to keep the forward momentum going without any signs of fatigue, and Aja keeps the buzz going with lots of nudity and gore littered throughout, with very few moments where there is neither.
The one-line explanation of the film - "flesh-eating piranha attack spring breakers" - is enough for Aja to get what he needs to do. The actors get it too - everyone is straight-faced and utterly serious, and yet get the campy tone exactly right. Adam Scott gets to be an action lead, and he delivers in spades. Here's a man who is a successful comic actor and yet can take the film on his shoulders for extended periods in the film. He is convincing doing ridiculous stunts, and that's all it really takes, does it not?
Christopher Lloyd makes an appearance as the scientist who delivers exposition, and is completely fun. It's Christopher Lloyd, I mean. He can be interesting and manic and completely himself while saying lots of things about crazy fish that eat people, and make it the highlight of the film, which he so does. Aja has done some brilliant casting - he knows that the exposition part of the film is the most boring and tends to drag the film down, so he makes it more interesting by casting The Doc.
This continues on with the rest of the crew - Elizabeth Shue as the strong sheriff lady is very interesting and completely charismatic. Her interest goes beyond saving random people as her kids are stranded, too, and even with the campy tone perfect she can get across her concern. Jerry O'Connell is suitably creepy, and we get a great payoff when he receives his just desserts.
This is the meat of the film - the gore, the spectacle and the schlocky campy fun. You'd be surprised at how much Aja has gotten away with in this movie. He keeps the film going and keeps escalating it with increased violence and gore, culminating in a cinematic orgasm of blood viscera and debris.
The shortcomings in the movie are all technical - the horrible CGI works in a campy way sometimes, but mostly it is rubbish. The 3D is awful too - post-converted 3D has never worked before, and Piranha is no exception. Despite that, you know if this film is for you: if schlocky, campy humour with lots of gore and nudity pushes your buttons, be in line. If it offends you, stay away, 'coz it's got nothing else.