I was looking for a night in London and with this voucher my total stay costs me only$5/£3. 🙂 In order to receive the $35 you will have to use this link and sign up.
I checked prices and compared few sites with TravelPony and they do have good deals. Especially if you live in major cities or in the US.
Tip: Always check and compare prices, with other websites. With most hotel aggregation website you will not receive points from loyalty programs.