Borderlands is superior to Rage in every way but one: its looks (and actually I prefer the cartoonish landscape of Pandora - but Rage is indeed a masterpiece, visually).
It was better written (certainly much funnier), longer, better driving mechanics (by a mile), better weapons, free roaming, more side quests (not the two hubs with three missions each), more fun.
I wanted to like Rage very much, and I do - like it, that is.
It's some good shooting fun that could have possibly been among the greats if only some things had been done differently.
If you make a game that looks like yet another open world dystopia - but drags you by the hand through the gameplay you are going to hear some gripes.
HL2 was a perfect example (at least to me) of a railed game that (by way of distraction and clever landscaping) never really felt linear. If there's a building, fence, wall, etc. in my way then I move on - usually not even consciously - toward the next point.
But there are so many places in Rage where it looks like you can, and should, be able to travel - but Rage says "oh, no you don't" with a broken step or (more often) an invisible wall.
Felt lazy to me.