I set up a phabricator instance for testing it out, seeing how it works. It's slightly confusing to get started with, and the UI is a bit confusing, but it does seem rather useful. The repository browser isn't very user-friendly though, and I'm considering keeping my CGit setup for browsing repositories. The setup documentation also doesn't mention how to set the repository path, or where the default one is located, so that was a tad annoying.
For now I'm considering moving all my repositories over, though I will have to consider how to set things up properly. One annoyance is that the bugtracker doesn't have a way to tag bugs with a repository so that you can search by repository. You can tag them with projects though, so I might end up having to create a project for each separate repository? Alternatively doing something with spaces, though I'm not sure if I understand those properly yet.
(It being implemented in PHP is also a slight turn-off. ;))