The reviews are in on Borderlands' latest DLC - Mad Moxxi's Underdome Riot and the Xbox 360 version seems to be averaging out at about 65%. Giant Bomb is the harshest critic, rating it a 2 out of 5, saying that it all feels pretty pointless.
Completing Mad Moxxi's Underdome Riot will get you two additional skill points, and there's also an item bank, which lets you store any of the weird weapons you've found, but don't want to actively use. These are nice benefits, especially for players who have hit the level cap and are looking for something--anything--that will let them advance. But everything in the Underdome is a total hassle, and that gets old fast. That you don't gain any experience points or build up more weapon proficiency while in the arenas only makes a bad situation worse, and it makes the entire experience feel pretty pointless