I book ~200 room-nights per year on priceline and have had my share of bad experiences (ooh, that LAX Hilton!), but on the whole, they run a pretty good service, if you know how to play right.

One area where I am careful to exercise extra caution now, due to a number of mishaps, is keeping a careful electronic trail (complete with time-stamped screen shots) in order to resolve problems with Anything points not posting properly.