JohnnyDollar: Gearbox has released a ridiculous amount of micro dlc, and what looks like a few story dlc's.
@anyone
How is Borderlands 2 vanilla without any of that stuff?
If you like the Borderlands gameplay concept, you don't need any of the DLC really.
You can probably easily spend anywhere between 20 and 50 hours on the base game alone, even using just one of the characters.
If you love it that insanely much you'll probably want the DLC, which you can always pick up during a good sale.