I have it working with LDAP + ssh access (a la GitHub, everyone uses the 'git' account to push but uses their own keypair for authentication). The review system works quite well, and one thing that I hadn't seen in other systems is the ability to "squash" revisions -> while the code is being reviewed and updated, once it's finally 'landed' into the repository all the diffs can be squished to a single commit rather than having multiple commits correcting eachother. One of the nicer things about running Phabricator is that it has quite a bit of documentation, and
I've been quite pleased with Phabricator, and the bright people working on it are always helpful in the IRC.
The largest gripe I have with Phabricator is the UI is a little tedious at times (multiple page navigations for doing some things which feel like it could be simpler, etc.).
You can create yourself an account on their hosted version, and browse their development of Phabricator: https://secure.phabricator.com/
Edit: One other thing I wanted to point out which Phabricator does that GitHub/GitLab and others do not appear to - Phabricator starts to form a model around "Ownership" of code which has been useful on a large project. People can elect to be notified when areas of code change that they otherwise would not notice.
One of the nicer things about running Phabricator is that it has quite a bit of documentation, and..
..and the install provides really great feedback about how it's running. Server issues are identified and displayed to logged-in administrators, so phabricator actively analyses its status and any reports what actions might need taken. The upgrade process is really smooth as well.
We use gitlab as a replacement for gitosis and in that workflow there is no longer any room for phabricator.
But now that phabricator can self host repos it is a big plus. They should rework the GUI, it is my biggest gripe at the moment.
What I miss in all tools I have tried is to make a random comment in the source tree. I don't want to fake a branch to achieve that.
Once you get used to it, the Differential code review process feels very natural (better than pull requests, even).
Further reading:
http://gregoryszorc.com/blog/2013/10/14/phabricator-is-aweso...
Unlike Stash, GitLab, GitHub, Gogs, or others of that nature - though - it expects you to setup your git repositories elsewhere (at least the last time I used it) instead of acting as a receiving host for them (at least the last time I used it - which was a year or two ago at this point).
Bonus points that in encourages you to upload memes under macros to troll your coworkers when doing code reviews.