This was the first time I had written a design brief, or engaged designers and I learnt a lot from the process.
The only thing I didn't like was the amount of plagiarism in the comp early on (because all the designers can see all the submissions). 99designs suggested I switch the competition to blind which took care of the problem.
In retrospect I would have turned on blind immediately but as this was my first design competition and I didn't know what to expect. It is a lot of work keeping up with the feedback, but very rewarding in the end.
The polls are also very useful and super easy to use. I received many more submissions than I had anticipated, and the dual round selection process is very robust, offering you a lot of time to make changes. This contest was very good value.
If you are like I was, having not done this before and nervous about putting all your eggs in one basket with a single designer, running a 99designs competition is by far your best option I think.