This game is a stroke of genius.
Gameplay: Just Cause's gameplay is a mixed bag, with more good then bad. For the most part, everything feels spot-on, the cars handle fairly well, though they have a tendency to spin out rather easily. One of the biggest complaints I've heard were about the autotargeting system, but I found it to be pretty good, you can still manually aim at stuff, it just makes it easier to hit people. The main problem I find is the game's vehicle hit detection. On more than one occasion I could be happily driving along the beach, and i'll hit a small pole and BOOM!! I no longer exist. Other than that, the gameplay is solid. The Skydiving/parachuting mechanic works extremely well, and the grappling hook adds a lot of fun.
Graphics: This is where this game really shows it's stuff. The Island is huge, roughly ten to 12 times the size of San Andreas, and it all streams off the disk. The draw distance is amazing, from high enough up, you can see almost the entire island. And what an island it is. San Esperito is chock full of detail, filled with lush jungles and cities, and all of it is completely explorable. The lighting is absolutely beautiful. It's amazing how the different times of day completely alter the landscape. Take the ocean, it changes colour accordingly for the time of day, and it's amazing to watch.
Sound: Probably the games' weakest point. The gun effects are decent, and the voice overs aren't anything to brag about. The game would've felt so much more immersive if it had a radio system. A couple channels with some decent music would've really helped. While the music in there is pretty good, the game needs a couple of talk shows or something.
Lasting Appeal: This is another low point, once you beat the story, there's really no incentive to play through it again, and there's not a huge amount of side activities to do, other than some races and liberating villages.
Just Cause is overall an extremely good game, and just about everyone will enjoy it, it's got something for everybody.