I used them about 5 years ago - I think I booked The Silverton. Since that time I've never seen their prices any lower than Expedia/Hotels.com....so I've never used them since. But I had no issues. Reservations are pretty much a commodity anymore so just go with whoever gives you the cheapest price.
What pj said just different hotel. Also, if you play enough to warrant possible comps going through a broker like this eliminates the possibility of getting the room comped.