Borderlands was a great, if not, amazing game. I never had so much fun playing an FPS. Maybe it's because I have grown to resent the typical "military" shooter, but I really found solace in the way Borderlands was formatted. It was an FPS with RPG-like elements, and these two things were thrown into a crazy art style (cel shaded glory, baby). It also helped that the game was CRAZY. I really do like some crazy thrown into my game.
This video is about 5 minutes of Borderlands 2, and while that may excite you (as it should), don't set your expectations too high. This gameplay footage is very much similar to what you have seen already from the first game. Yes, there are new enemy types, but nothing looks drastically different. Let's just hope the end-boss is a little better this time.
Is more Borderlands what you want, or did you want a drastic overhaul?