So many other mattress protectors are a pain to put on and take off. I've put a hole in more than one from pulling so hard. Not Ghostbed's Mattress Protector Cover - it is generously sized and protects the entire mattress.
I've used it for about a month now, maybe longer, and it hasn't slipped out of place, hasn't needed to be pulled back over the corners, not once. Also, it isn't noticeable through my sheet, it doesn't feel like I'm sleeping on anything extra.