Skimming the other posts, I saw one or two positive things dragged out of them.
"To get a good review from uncov, you really have to earn it."
K said something relevant a while back: http://www.roadtoforbes.com/index.php/ksblog/why-the-80-20-rule-doesnt-always-work/
Anyway, even if they ARE utterly impossible to please, they're still telling you outright what you can improve. And an extreme view can sometimes help to put everything else in perspective.
That assumes they're being objective; so far, it looks like jealousy or other frustrations manifesting themselves.
It'll be interesting to see whether or not they do like anything in future.