I've also used the site a number of times for suggested prices only.
Then have also actually bid with it 4 times, but always higher than the low ball and lower than the max price.
Have never gotten a booking with it yet.
Priceline today says congrats they've upgraded me to a 3.5 star hilton instead of nearby 3 star doubletree for the same price.
What they don't say is doubltree is free parking, whereas hilton charges $17/day. Considering cancelling it.