http://en.wikipedia.org/wiki/Just_Cause_2
Tons of fun trailers:
http://www.gametrailers.com/game/just-cause-2/11068
I can't wait for this game. The demo itself has made this a must buy for me, you basiclly have 30 minutes to cause as much chaos as possible. Just from the demo and trailers it is obvious how much better it is than the original.
The map is massive, the demo has a 35 sq mile limit (which is pretty big on its own) but the actual game is 400 sq miles. Everything from Just Cause has been improved on, especially the grapple/parachute combo. You can grapple only anything and hooking any two things together which can make for some epic kills (like hooking a soldier to a gas tank, shooting off the cap and watching them fly away.)
This is definetly not mean't to be a serious game, it's all about the freedom to do what ever you want and all around epic gameplay. If you havn't tried it yet, download the demo.
Release date: March 23rd