Summary: The weakest of the DLC for the first Borderlands game. This DLC is definitely intended for co-op as playing alone feels like an overwhelming waste of time. Repetitive wave after wave of bad guys makes this one mediocre at best.
Summary: This DLC is the exact opposite of what Borderlands is all about. Instead of unique environments, funny quests, leveling up, and lots of loot, Moxxi provides tedious arena combat for meager rewards. The matches are way too long. The random modifier system can result in stupidly hard situations.
Summary: Totaly crap. You dont earn exp at all, you only get a few loot items at the end of a round... the only real reason to get it is for the bank and upgrades that are available to purchase. Stay away.
Summary: As many others have stated, this DLC takes probably the most lacking part of Borderlands (i.e. the shooting) and puts it in the spotlight. With no experience or equipment to gain, the core of the game is removed and make Moxxi's an unsatisfying DLC.
Summary: This is the perfect example of how NOT to do DLC, it adds nothing enjoyable and has no real value other than a way to play through a crappy Horde mode clone with your friends, it gives you three arenas and each one has 5 rounds each consisting of 5 waves and each wave is the same every time you play...
Summary: Fun for 5 minutes, then it's just boring and annoying. They didn't even bother to add new monsters or even try to properly balance the game for single players... Neither worth my time nor money.
Summary: I'm thankful I got the GOTY of Borderlands, as I would have been furious if I payed for this DLC. All the fun of repeatedly killing constant monotonous hordes of enemies with random ambient environmental effects, without all the hassle of leveling up and improving your character!
Summary: This is the opposite of fun. In fact, this DLC is work, grindy, grindy work. If I had wanted to play grindy games, I would play MMOs. Even more importantly, you hardly get rewarded for the time you put into the arenas which comprise 100% of this abysmal abortion of a game.