Tell me about Borderlands...?

I've heard some good general buzz about the game, and I have heard that there's a sequel out or coming soon, but I've never played it or seen it played. Is it a game I'd enjoy?

Games I've played and enjoyed:
  A bunch of the JRPGs, with Chrono Trigger and Star Ocean and Persona at the head of the lists
  Fallout 3 and New Vegas
  Oblivion and Skyrim
  Dragon Age

Games I have enjoyed but found I can't play them for long before my aged reflexes betray me and I am filled with fail:
  Action-RPGs like Tomb Raider and inFamous

Games I don't really enjoy are FPSs.

  I've also been thinking about Mass Effect. Is it important to play ME1 before ME2 and ME3 or are they pretty much separate?