I've used Hotels.com for years - love the fact that you get a free night for every 10 nights booked through them, so in effect a 10% discount on every booking.
Just recently I've seen that I have a cash reward, and having looked in to it and spoken to them via chat, I can see that now the reward is 'cash' rather than nights, and equates to 2% rather than 10%.
Bit of a letdown, and I haven't seen it publicised - just thought others might also be interested. I get £19.14 on a booking in excess of £1,000 - bit of a disappointment!