I was doing Net Galley a few years ago, and had a mixed bag with it. I got some good reviews but some really horrendous reviews too. It's like they review in the extreme, no middle road.
I had paranormal romances, erotica, and erotic romances. I got tired of the 2 stars for my shorter novellas. People were really down on shorter works to read. Since I was writing more shorts at the time, I got out. I was in a timeshare deal, and was sharing with other authors. After about a year, I decided to try somewhere else.
Then, the great review purge started at Amazon. And I've lost a few anyway. I don't get with what is up with the Zon lately. But hey, I've just noticed a huge drop in reviews overall. So, I'm not beating myself up for them anymore.