I haven't personally used one, but i prefer to stick to hand-sanding. It can be a bit exhausting at times when trying to sand larger areas, but you have way better control. All it takes is one slip with a power sander to mess something up, or get an unexpected result which you may have to later repair, and yes, re-sand.
Granted i hardly think this device would do severe damage, but i'm fickle and like to stick with my trusty sandpaper.
Not to mention, i could buy a whole lot of sandpaper with $68 bucks that would last me forever. It also looks like the only paper available for that is 100-grit at $4.50 a pop?? Ouch!
Sure you could glue different grit paper onto the attachments, but hardly seems worth it.