The original Just Cause was a exceptional game let down by a lack of things to do, repetition was the order of the day and while it was fun it also got a little tiresome after a while. The sequel is a huge improvement, now the game involves a lot of blowing things up and general destruction and we all know that never gets old.
Some the sounds are a little off, drive a car that is falling apart and the noise is awful, while this may be accurate it is not very pleasant. The other sounds are great though, guns sound good and the ambient noises are good too.
The Gameplay is fantastic. They've taken the same approach as Volition, they know given a sandbox to play in gamers want to mess about and break things. You can spend hours ignoring the missions, choosing instead to just go about exploring and wrecking the place. The missions themselves aren't too bad, as before it's all about taking control of areas and helping factions, I won't say more because I don't want to spoil it. Those who like collecting things will be heaven, there are a ton of things to collect that do things like increase your health and upgrade weapons and vehicles.
Now for the only downside, the mouse/keyboard controls feel sloppy. Everything feels too loose, it hard to put my finger on exactly why but others have made the same observation. The game does work fine with a 360 controller so I would suggest using one of those instead.
All in all this is an excellent game that I would recommend to anyone, it's one of those rare games that mixes excellent gameplay with spectacular graphics. The game engine is fantastic, I'd love to see Rockstar and Bethesda use it for their open world games. Oh and no Nazi style "always connected" DRM.