Now, the only reason i brought the first title was due to the offline split screen co-op. Since the days of Conflict:Desert Storm on the PS2 (and not the terrible Denied Ops on PS3) me and a friend have enjoyed killing bad guys and pretending to be super stealthy killing machines...
Now, the first one, i really enjoyed, it had its glitches, bugs and poor design...But i enjoyed the idea and just got through the problems.
Army Of Two: The 40th Day is one of the most improved games of all time (in my opinion of course...and after Assasins Creed 2). The game handles a lot better, the weapon customization has been overhauled (and who doesnt love impaling Mercs on a screwdriver?!).
To me this is a fantastic game, whilst there will be some people who dont like it (and there are 7 single player missions which will take about an hour each on the hardest difficulty, and depending on how good you are), but if you have a friend by your side (or over PSN) you will enjoy every last minute of this game.
Now, as for giving it 4 stars instead of 5...Multiplayer. I never had an preconceptions that the multiplayer was going to blow me away, but, from what i have played of it, it has a long long way to go to be taken seriously.
So, in a nutshell, this is a much improved game than the original AoT so do not let any negative experiences of that game (floating hovercraft anyone!?) put you off at least renting this game. You wont find a better way to have fun with a friend...no rude jokes please!