Anything <= 10% is worthless. You dont earn rewards for using this coupon, and without using a coupon, everyone gets 10% on accumulation.
If you're one-timer on Hotels.com, then yes - anything >= 0% is worth...
On the Hotels.com facebook app, you can unlock 5% - 50% off:
Book by March 2013 | MYSTERY DISCOUNT COUPON
Only 1 coupon per app user. Coupons can be used for travel between 2/18/203 and 3/28/2013.
I got 10% off