Gearbox could give a keynote address at this years' Game Developers Conference on both what to do and what not to do in downloadable content packs. That's because they now have a good example of each.
The Zombie Island of Dr. Ned (the first DLC for Borderlands) was some of the best DLC I have ever seen for a game. It added plenty of quests, a great narrative, it had a sense of humour, there were lots of new things to kill for precious XP, and even some nice loot dropping monsters. Now we have Mad Moxxi's Underdome Riot, which is the complete opposite.
You will find no narrative here, no real quests or any reason to laugh. All you get are three arenas where you fight wave after wave of enemies while different random attributes are added each round. Things such as "no shields", "enemies move faster", "less gravity", and so on . The concept behind this is fine, as anyone who has played Halo: ODST's Firefight knows how much fun this can be for a shooter. But therein lies the problem: Borderlands was never just any other shooter. It's a shooter/RPG hybrid, so making this all about the shooting takes away a lot of what made Borderlands fun, and exposes the shortcomings in the game's shooter mechanics.
You will gain no experience points for killing things here, which means most people won't bother looking at it until they have reached the level cap of 50. You will hardly ever find new weapon drops; yes, sometimes new weapons will appear but they will not be any good for a level 50 character. Except for Mad Moxxi giving a bit of trash talk in between and during rounds there is no story. Moxxi as a character seems fun, so why on earth they did not include more of a back-story with her is beyond me.
Also, good luck to anyone planning on actually finishing this DLC, because it is damnedly hard. The difficulty scales to a point where my three friends and I were dying so much it killed the fun. Killed it with a shotgun that fired rockets… rockets that carry poison inside. You will be surrounded by enemies who are tougher than you, do plenty of damage and with all the round attributes it can become very unfair. We had a round where we had no shields and were losing health every second that we were not shooting at anyone. Forget the fact that if we got shot ourselves we'd lose almost a fifth of our health per hit anyway. This made staying alive next to impossible.
After such a great DLC release with Zombie Island of Dr Ned, I struggle to understand how Gearbox could have gone so far astray with this one. It is frustrating instead of fun, and the lack of experience and loot drops ruins the qualities that made Borderlands so special to begin with. You do get an extra skill point if you get far enough, which is nice, but hardly worth the frustration you will go through to get it. There is also a bank system introduced for storing more loot which is a handy addition to the game even if many people are not going to use it that much anyway.
I loved Horde mode and Firefight. However, I do not even remotely like Mad Moxxi's Underdome Riot. If you liked Borderlands because it was Diablo with guns, steer clear of this one, and if it is too late and you already have it, please try not to let it ruin your initial feeling towards Borderlands. Hopefully Gearbox will give us another great adventure for the next DLC as they did in Dr Ned. Then we can pretend like this never happened.