Clever, well-acted, and with a few legitimate scares along the way.
It ultimately falls victim, however, to the usual "found footage" disease, wherein one is supposed to accept that people would continue to use their laptops/camcorders/iPhones/etc. while they are being tossed around the room with their lives at stake. (Honestly, if ghostly footprints are heading my way, the LAST thing I would be doing is transmitting it through my webcam.)
Still, if you can suspend your disbelief enough, this is a lot of fun. And blessedly short, too. There are definitely worse ways to spend an hour of your time.