I havent payed much attention to rage, looked like a usual brown fps. But pparently it has some rpg elemnts, I have looked around and watched youtube vids. But cant really see anything. What are these people on about ? DO we level up and customize weapons or something ?

Loot, engineering schematics to build new weapons. No real level up system but there are shops and hub towns. Lots of exploration and I'm guessing from the stuff you get from preorder you can swap out armors and stuff to get a nice neat looking character.