I also signed up for the site but it seems a bit risky to me at this point. I recently got an email from them saying that they were having a sale on the Khs and you could use a promo code to get 10% off...but you still have to spend at least 0.02 BTC so I am not convinced it is worth spending for. This could just be a way to get people to spend money sooner and then the site will disappear :/

On a related note, most of the things I have read about cloud mining are that it is not profitable for the person buying/renting the Khs/Ghs. I haven't really looked into it that much (as far as doing my own calculations and whatnot) but I am not convinced that it is worth spending money on currently.