Just Cause 2 is a TON of fun. If you get it for the PC, you are making the right decision. The console versions just suck (played the 360 demo). The world size (while several MMOs beat it) is GIGANTIC, but still navigational.
The story is good enough and keeps the missions in check, but outside of that there isn’t much there in that department.
When you do beat the campaign, there are plenty of areas to explore and tons of easter eggs. I’m probably 53-80% done with the game and there are still things to do. JC2 is a time investment, but it is a fun one. Plus the mods are great.
This is a game to mess around in. You are given tons of guns and vehicles with the simple objective of “GO NUTS”. There is never a real dull moment in this game. You should get this game.