If the award search engine were good it would be worthwhile. I'm not sure the claim "UsingMiles is the World’s First Search Engine for Award Travel" is really fair -- (1) airlines certainly offer search engines for award travel, (2) Randy's team built one for Mileage Manager a few years ago.
I've been using the site for a while now and was even grand-fathered into Premier status because of this. I use it regularly and it's decent, although I basically just use it to keep track of balances and not for award searches.