MaxFisch used to be the gold standard.  Tons of Domme listings and reviews, but it's a shadow of its former self.  Still can be useful.  Go to the "Hang" and you will have forums including reviews.

With the efforts of our members, perhaps TER can become the new place for Domme reviews.

While there are several sites with listings of Dommes (i.e., where to find them), most of these sites are also supported by the providers advertising on those sites; thus, they have little, if any, incentive to provide unbiased reviews.  As a hobbyist-supported site, we are probably in better position to accomplish the kinds of review that would be meaningful.

Our colleagues on the Transsexual Boards aren't ashamed to post their reviews.  I hope that our submissive/bottom hobbyists will follow suit and start to feel more emboldened to post reviews more often than we currently do.  

I've found that Maxfisch.com is high traffic and active, however Domboss.com/messageboard is sometimes more thoughtful and in depth.

Best wishes for your search!