The restrictions that are inherent with their airline booking do seem to scare away quite a few people, but I was very happy with my experience with them when I got a last minute ticket to West Palm Beach from New Orleans for $185 instead of the $500 I was getting quoted everywhere else ...

Also, I think the hotel business may hold even more promise, because you can designate the location and quality pretty specifically, the proposition looks much more attractive. I have also heard of nothing but good experiences so far from people using the hotel booking service (with the prevalent theme being "I can't believe what a nice hotel I got for the price").