I have one. I used it quite a bit when building my home and cutting outlet holes in sheet rock. As you would suspect it's great not dragging a cord around or finding an outlet. The battery lasts fairly long and it isn't terribly heavy. I use my corded Dremel more often but this one has its place.
I have it set up on my workbench with a cable drive attached. I usually end up taking the work to the tool instead of the other way around. My corded Dremel (actually I have 2 that are identical) are pre-XPR. If the work is a little more intensive I use a Roto-Zip. I had my corded units before I bought the cordless and kind of got used to them. It's just kind of the way things have worked out for me. I've also never tried to attach the cable drive to the cordless. Guess I ought to look into that. These are the models I have. I've got about every accessory available for the first one, cables, router, complete bit sets, hanging frame and the list goes on.