Our local instance is only a version back but we find gitlab to be terrifically slow, and regularly have to kick the server as we find it stops tracking updates, then simply stops responding at all. Also, the diffing on merge requests is simply awful. It regularly shits itself on spacing changes and the like making most merge requests almost useless from a code review perspective. Searching just doesn't work. At all. Navigation is weird and cumbersome, with many normal features hidden away in different sections of the UI. This causes weird situations where, since search doesn't work, I have to just browse around for commits to a branch I want view at a certain state, and click that commit to get to a "brows code" view. Why the fuck isn't there simply a repo->branch->commit history->browse code path?
I personally wouldn't recommend gitlab and hope someone else is out there working on something better.