Which model of the Rotex did you get? They come in a few different sizes.
The big one can really be a beast until you figure out how to time it - has to do with speed and intensity of the vacuum. Then it can sculpt a Maloof rocker or buff the wax on your car. Very versatile.
Lots of info on it at www.festoolownersgroup.com
BTW, Festool wants to sell you big boxes of sandpaper, but many of the dealers will sell a few sheets at a time. Also, there are several other brands that will work on them, especially the ones with holes scattered all over the disk.
Good find. Congrats!