Reviewing Borderlands is difficult. New games are challenging our perceptions of what makes a game good, and the games are changing faster than we can change the discussion. It's not that Borderlands is challenging the standard of gaming (despite being an innovative mashup). Any comparison to Diablo is well-earned, though mechanically they're totally different they appeal to the same primal instinct of collect and improve. Plus it's an FPS. The difficulty comes when you try to quantify How good is it exactly? and end up with apples to oranges comparisons. Borderlands is fun but lacks the emotionally charged narrative that many modern games are able to provide. Should that be considered a failing of the game, which otherwise excels in being what it is? A question which provokes the discussion on what games are and where they are going and whether or not game-ness and narrativity are inseperable or in fact completely separate.
Suffice it to say I've probably had as much fun with Borderlands as I did with Mass Effect (a game I boldly suggested was the best game ever made), but I did not get as much out of it.
I learned that while it's fun to play online with friends, public games invariably have one guy who puts the I in team and consequently, the F.U. in fun. Also, final boss issues (how's Brick going to use his action skill in that fight?).