As a Co-Op game to play online with a friend this game is a must. As a single player experience it is perhaps at least worth one play through.
It is a vast improvement on the first game, I really loved the weapons customisation and the new game play elements such as act as a hostage, fake surrender and such were really cool (Especially fun when coordinated with a friend via an Xbox head set).
Graphically superior to the first game and most of the issues that fans fed back seem to have been resolved (Game play mechanics and hit detection etc).
I would highly recommend getting this if a friend has it already as it's best played coop and If you are into 3rd person shooters then this is well worth your time at least for 1 -2 player throughs in co-op.