I'm opinionated on this since I'm running GitLab.com where you can use GitLab as a service.

GitHub has more features than GitLab. GitLab does have all the essentials to work as a team including merge requests and CI integration. Personally I think the GitLab interface is a bit less cluttered.

A list of things that are still missing from GitLab can be found on http://gitlab.uservoice.com/forums/176466-general

The highest votes items there (namespacing) just got added in GitLab 4.0

And the lead author Dmitriy had added many improvements each months for the last few months. Also the number of good pull requests is steadily increasing https://github.com/gitlabhq/gitlabhq/pulls?direction=desc...

If you want to run your own server you need to understand basic Unix systems operations. If you are comfortable with the installation guide than you should be fine https://github.com/gitlabhq/gitlabhq/blob/master/doc/install...

The main feature I'm missing is forks/pull-requests across repos. It's a nice way to keep strict control over the main repo while allowing others to commit code at their leisure. I must admit that this took me a little by suprise after installing GL.

Consider voting for this functionality at http://gitlab.uservoice.com/forums/176466-general/suggestion...

I actually tried, but was greeted with a "Sorry, but we couldn't submit your vote." Something is broken but that's not gitlabs fault ;)

I guess UserVoice ops is on a well deserved holiday :-) https://twitter.com/UserVoice/status/282207838149943296