We currently use Review Board for code reviews, but over the last year I've found new releases increasingly buggy. Especially since upgrading to version 2.x, it seems mercurial support isn't getting much testing and it has resulted in users getting frustrated by random errors like the diff viewer throwing exceptions, and uploading diffs via the web interface not working (apparently everyone should be using RBTools) - support for specifying parent diffs was even removed.
I know Review Board is a popular tool, but I was wondering if anyone knew if there was a better alternative which supports mercurial? I've not used it yet, but from what reading I've done Phabricator sounds good - almost too good to be true. Since we've been using Review Board in our department for 3-4 years and now have thousands of reviews, there's a large resistance to change, and I'd like to try to ensure we'd not be jumping from the frying pan into the fire with any change.