Love it
Only played multi-player atm but I had a blast.
It took me about an hour to figure out what was going on and then it really got good. Me and my friend played for about 4 hours and by the end we both said it was the best game we had played in ages.
Here are a few things I liked
-Gun modding
-Bullet-time (jumping out windows from the second level of a building and smashing someone in the face in bullet-time is awesome)
-Heaps of different upgrades
-Challenges
-The maps are well balanced and look awesome
-You unlock alot of MP weapons and skins in SP which I think is a good idea.
-Rookie teamdeath match servers with a level cap so you can learn without getting smashed.
-Gang Wars is a great way to play
-NO ONLINE CODES NEEDED TO PLAY
-On the run upgrades (call blasts) change game play. You can modify these as well. I had trigger happy which has 3 levels. Top level is grenade launcher

. You get it after a couple of kills in a row.
I bought the game at BigW for $68 but I would have paid $100 if I knew it was going to be this good
Go get it

and get ready for a slap to the face in bullet-time from me