I was hugely disappointed with Borderlands, so much so that its lead me to dub it "Boringlands". In co-op it can be a great game but thats only because its your friends making it fun. The game itself is incredibly dull and after the first hour things just get repetitive. It really is just like an MMORPG but without the horde of other players to mix things up a bit.
One of my friends, a huge fan of Borderlands, argued that its not going to be as fast paced and action filled as your typical FPS games due to the RPG element but I respond, "Why not?". Games like Deus Ex and Fallout 3 became hugely engrossing by merit of having a decent storyline that involved the character. I appreciate that this has to be sacrificed slightly due to the co-op nature of the game but thats just it; its like they've put so much effort into making it co-op friendly that all you really have is this wide open desert with the usual fetch quests and respawns.
The graphics are all very pretty of course and the characters are vaguely interesting but the "atmospheric" music is awful, being that of the same few notes playing over and over again (now that I have mentioned this, if you haven't already noticed then you will now!).
Overall, I regret paying £30 for it. Would have been cheaper just to load up Fallout 3, remove the storyline and add an orange hue to the landscape.