In my opinion, Just Cause 2 is really not a good game. It suffers from lackluster controls and has a narrative that should be reviewed by badmovies.org. I really have no idea what is going on in the game (I've skipped every single cut-scene so far) and its hard to take a lead character seriously that sounds like Triumph the Insult Comic Dog.
 
So why do I (and others) keep coming back to it?  Is it the beautiful setting (Panau look gorgeous)?  Is it the expansive open-world?  Is it the grappling hook mechanics?  I think, quite simply, its the addictive gameplay.  Blowing stuff up, driving/riding/flying anything in the game from the start, generating chaos, etc...  The Just Cause 2 DLC feeds my addiction like a junky scoring from their dealer.  A quad, lock-on missile launcher you say?  A new fighter jet to grappling hook an enemy to and fly at break-neck speeds you say?  Parachute, jet-pack thrusters you say?!  I say sold.
 
The quad rocket launcher works well (its very easy to lock on and fire) and is powerful enough to destroy many of the vehicles and structures in the game.  The fighter plane is exactly that, a new jet to fly around and cause chaos.  Probably the best part of the DLC are the parachute, jet-pack thrusters.  Yes, you heard that right... JET-PACK THRUSTERS to extend your hang-time and increase the speed at which you traverse Panau.  The thrusters have a limit at which you can "fire" them designated by an on-screen gauge.  Once this gauge is depleted, you will have to wait (albeit a short wait) for it to recharge.  The only problem with the enhanced parachute is that you will have to purchase it from the black market after every time you die.

I've been playing the game for nearly 30 hours now and have completed only about 25% of it.  The DLC for this game will keep me playing it simply because it gives me a fresh way of generating chaos and new and creative ways of dispatching the enemy NPC's.  My only gripe about the DLC is that it probably should have been included in the retail version of the game.