An intensely satisfying run and gun FPS with lots of variety, but sadly lacking a good story despite great characters.
Unfortunately, that opening theme is about as deep as the game gets emotionally. These characters barely speak at all throughout the game. Barely speaking just to comment on lack of ammo or your choice of weapons. The only attempt to breath life into these people come in the form of ECHO recorders that give some background to each one. These are mere optional easter eggs though, the developers not interested in making you care about them in any way.
The story is really quite bland. You are vault hunters... you're questing to get to a vault. Handsome Jack, the antagonist of the series, has plans of plundering the planet for resources and killing vault hunters. These people don't really have interesting motivations, so the story remains one-dimensional and almost an obscure who-really-gives-a-crap thing off on the horizon.
All that is okay though. Because this game's focus is not on an interesting story concept or deeply developed characters. This game is about fun. A lot of fun. In a variety of witty, humorous, and challenging ways.
While the main characters are just short of being Gordon Freeman with special abilities, the rest of the characters are vastly more entertaining. Each and every character you meet is equipped with witty dialogue and superb voice acting. Even if you don't care what tasks they put you on, you want to listen to what they have to say just for the sheer joy of listening to them.
The real meat and potatoes of this game is the combat. Whether you're playing with friends or alone, this is not going to be like your usual first person shooter. There are a gazillion randomized weapons with a vast array of special traits designed to fit different play styles. And even better, you need these variety of weapons because the variety of enemies will require different strategies and weapons. Some are fast, some are slow, some come in groups, some have shields, some go invisible, some fly or can only be attacked from behind. That's just the beginning of it. The creatures and crazies you will meet in Borderlands 2 all have different creative strengths and abilities, different ways of taking you down that you need to be prepared for. You too will have different abilities, different classes with skill trees that you can customize to your liking.
In the end I think this game succeeds at doing exactly what it planned to do. Entertain and challenge you tactically. I think a deeply developed narrative with intriguing characters could have only made things better. It's a shame that such a vastly interesting world wasn't used to its full potential here.