'Tis good! I haven't tried any other of the rsbrs, but what it does is provide you with a lot more content - loads of cars, a few tracks and some mods. To start it up, you open a program called 'RSCenter' and you get various options - what car, what track, what mod (night, all tarmac, gravel, snow, normal...), what weather, damage and whether you would like to play alone or with other people! I haven't tried out the online stuff yet, but you can participate in various leagues and single rallys etc. Then you click on a button, which opens RBR and you start on the config you selected in the RSCenter. You also get your stage times in RSCenter.
It's a faster way of applying new cars/tracks/mods and provides an online multiplayer service, basically.
I love the tarmac mod!!
I only downloaded this ~1 week ago, and got RBR for christmas, so there's probably a lot I haven't tried! What should an RBR noob do now?