As a writer, I embrace concrit. That's not to say that the criticisms don't sometimes sting, but if I'm honest about wanting to grow as a writer, I need to hear what doesn't work. It doesn't help me to only hear praise. I won't know where I need to focus, and I'm one of those odd people who doesn't want my email address out there for the world to offload their musings onto.
I've gotten concrit, and I hope to get more. I'll give it where I think it's needed unless an author asks that they not receive it, in which case, I probably won't review at all.