I am lecturing at various universities and consulting corporates on webtrends like Crowdsourcing. 99designs is always part of it. So far, I have never experienced anyone in the classroom or in workshops who was not impressed with this site. As for the designers, I can only say the best. We have run 3 contests so far and always received the perfect value for the money invested.
And what i liked most is that we as well could start kind of a relation with the designers and make them part of our project which i believe is so important.