I don't think there's any RPG element to Bioshock.

The whole good/evil choice is pretty lame (though overall the story and background kick ***), and there's no character customization. Upgrading your guns, improving spells and getting more total health don't turn a FPS into a RPG.
Fallout 3 does have many RPG elements, Bioshock doesn't.

The only reason why Borderlands might be described as similar to Bioshock is for the distopian world, not for the gameplay mechanics IMO.

Overall, the game looks interesting. I might give it a try.