You only need watch the intro and pass its fancy character select screen before you've fallen in love with Borderlands. You will have chosen whether you want to be Roland the Soldier, Mordecai the Hunter, Lilith the Siren or Brick the Berserker.
The over-arching story to Borderlands is pretty basic. You have to find The Vault, if it exists. Spoiler: It does! (Although this is obvious from the intro). The world of Pandora is a colourful wasteland populated with half a dozen different enemy types with a lot of variation within. It's all so very Mad Max inspired that there's a boss character by the name of Mad Mel. Mad Max never had skag, rakk, spiderants or temple guardians to contend with though.