The beginning is promising. Satan is quite spooky sitting by Jesus, and it seems like they are going to have a talk when the Devil starts saying 'I don't think you can handle carrying everyone's sins'. A-ha, so there is a story about 'is it possible for one man to carry so much weight? Can God want that'? But there is about 7 minutes of decent cinema in the entire film. Instead of answering, Jesus just collapses to the ground moaning and gasping. Not many 'ideas' in the rest of the movie. From then on, the film is basically the guy getting a beating that is enough to kill a man in 5 minutes. How can you take it seriously?
In the bible Jesus spoke quite a lot, and his sentences are considered the most sacred moral teachings in our (Christian, of course) society. But in 'passion', the Man hasn't much to say. He cries. He falls to the ground about every 5 minutes. He keeps his mouth open. He crawls. He rolls his eyes in pain. It does get kind of repetitive. By the time the cross comes, you stopped caring about the pain inflicted in Caviezel (his worst performance ever) because it stopped being a person about 70 minutes before. Caviezel is just the Thing that Gasps and Rolls his Eyes (TGRE). Mary mother of Jesus (terrible, terrible performance), John, Judas, Caiphas and a bunch of other people run around bumping into each other with perplex looks in their empty eyes while Jews make savage faces like monsters bashing TGRE and Romans look like savage apes flogging TGRE. When he fell down for the 4th time in slow motion (gasping and rolling his eyes, of course), I just yawned and said 'I get the point, nail the (expletive) already'. Ah, and there are some short flashbacks. Lots. Do you care about them when you watch? Not really. The first one is completely out of touch with anything biblical. It shows 'Jesus' being a 'common (middle-class American) man', working in carpentry, making jokes and tickling a woman (his mom). Character development! Absolutely ludicrous, a bad scene even if you like this movie. What else? Ah, kids in ugly makeup, as "demons". Kinda scary - and very pointless.
If the movie wasn't spoken in ancient languages, (the best decision Gibson could possibly make in his life) I would have completely lost all suspension of disbelief. Instead, I lost that suspension only when TGRE was in focus. Really, if this movie was spoken in English I would just regard it as a very, very expensive b-movie. But the dialogs in Aramaic and Latin give it a solemn atmosphere that the poor screenplay and directing could never give. Because of that, I yawned and laughed a lot, but I did not totally despise the film.
REDEEMING SCENES: Satan's presence in the beginning (further presences are just Kitsch or grotesque) and the flashback to the lord's supper during the crucifixion. It connected very powerfully the image of the crucifixion with the catholic eucaristy. For the violence, well, of course it is in the same level as other Hollywood movies. But in action and horror movies you usually don't feel the violence is real. Same here.
In short, a movie that is intentionally 'thin' in ideas because it is supposed to be 'felt' by its visuals. But for a non-Christian, the visuals are sometimes grotesque, sometimes silly - mostly random violence on TGRE and silly people with empty eyes doing nothing important. On the other hand, the movie appealed so much to Christians because it is a story they care a lot about painted in strong colors with all the Hollywood camera tricks and special effects mankind is addicted to. If you are one, don't miss it.