The randomly generated items was complete bull. It's not random at all.
The combat system is sub-par, hit detection is awful and being a console port the PC version suffers hugely when it comes to using/equipping items and general bugs/usage. The GameSpy REQUIREMENT was also a huge fat mistake.
It should have been a great drop in and play game but it's not simple enough for that but the complexities of the game are not all that welcome either. The different damage types could have been an interesting thing but they are also a hindrance.
Some damage types are completely useless versus some enemies and WAY too overpowered versus others.
On another note the stats of weapons are so stupidly bull it makes it impossible to make informed choices. Bullet counts, accuracy ratings, scoped accuracy ratings, damage type etc etc.
Spec a certain talent tree and you are locked into a certain field of weaponry and play-style. This works for a proper full on character progression game but Borderlands is not that platform. It should have been a FPS iteration of Diablo and it's a FAR cry from that.
Hacked characters and item duplication destroy any real on-line play outside of friends and you end up with a game which lacks re-playability with more annoyances than simple good gaming should have.
It was over-hyped, not shipped as advertised and too buggy for PC release.