To me, this game doesn't hold a candle to the first game, as sequels usually don't to games I love.
I played a gunzerker to level 34 in the second playthrough and the other three characters to at least level 20 in the first playthrough.
I have yet to see an orange weapon in the game. The quality of the loot just sucks compared the the first Borderlands.
Since they changed it where each character can use any type gun just as well as another, they took away tons of hours of replayability.
Also, the special skill of each class is just not as fun as they were in the first game.
The asassin's class skill just sucks and the sirens class skill was so much better in the first one.
Its a fun game, but just doesn't hold a candle to the first one.