I just want to take the opertunity to say that borderlands is awesome and I would recomend it to any co-op player, it doens't get alot of the cred it deserves from the mainstream medfia because it seams alot of people are only interested in multiplayer, like for example, the halo reach beta was multi player, what's that abbot? the demo should be aboot the game, not aboot fighting other people, i can do that in games I already have.
Borderlands falls inot that catagory of games that are soo fun to play and fall into a catagory that I like to call "Hangout games" such as the left 4 deads, the crackdowns, and from the demo i played; castel crashers seams like it falls inot this catagory as well. Games such as that where you kinda just play and hang out and it's fun to play. Those games are the games that are instant classics in my mind. Those kinds of games are must haves for any gamer in my opinion.
Plus Borderlands is evne centered around co-op, each player has their own special ability, but when all four classes play together it makes the team unstoppable-provided that each has the proper mods and skill tree points allocated. Plus with more players, better loot is found and it's just such a great exsperience to play it.
The replay value on it is very high too in my opinion, not just cuz of all the different kinds of guns, but also cuz it's soo fun to play.
I rank it up with the classics like Chrono trigger, Chrono cross, tetris attack, and E.V.O. I hope more people discover this game and all the fun it has to offer.