To be honest this game is not all its cracked up to be.
There is a lot of improvement in general gameplay such as the ability to swim, the inclusion of boats and the garage vehicle storage facility.
However the game is far shorter and smaller than the original Mercenaries title. This game includes only one map compared to two on the original and no longer gives the ability to start a new game but carrying over your equipment and unlocks.
Also, contrary to what is stated here the game does not include a multiplayer split screen co-op option. I have not tried playing online but offline no mulitplayer options were found.
In all a fun game but leaving you wanting far more replayabilty than is actually available.