I've seen that too. To be honest, the negative comments are about the lack of support once you're there - which seems to have improved now. I've been speaking to a lot of people who've been with them recently, all of whom say they were really good.
Yes, there is more autonomy involved with the project, than say, RealGap, or i-to-i, however I think that's a good thing because you'll be more immersed in the culture more (as opposed to being with a guide all the time.)
I was really worried about the company, but for the price, I'm definitely happy to be more independent out there. I emailed them today about my projects and they explained exactly who would be there, what times they're available, and their role in aiding the volunteers.
That's such a shame your place was full - where were you hoping to go? Have you booked it through someone else now?