Borderlands 1 is more or less a proof-of-concept game.
This is a game built on the success of that concept and improved. I really don't see how you can look at this game and say it's worse, in any way, than the first one. It controls better, the gunplay is highly improved, the character skills and the skill trees actually prove to be something of consequence now. The enemies are more varied in not only their design but how they behave. Seriously, leveling up a Goliath is a game in it's own. And this is all praise coming from someone who got shafted by a glitch that reset all his Badass rank and collectible skins/heads...and he had every single one of them.
Borderlands 1 devolved fast into a Crawmerax farm festival after all the DLC was released and really the only respite from the constant desert wasteland theme was Zombie Island.
Also saying this was PSO kinda made me lol.