Self hosting is fine... but only for an internal instance. The release cycle is pretty extreme, with a critical security update seemingly popping up every two weeks. I mean that's better than not patching the issues, but it still means you have to stay on top of it. Having an internal/private network instance doesn't actually help you all that much, but it still gives you a little more breathing room.

(and I know it might contradict my earlier comment saying that Github's release velocity is a plus, but it doesn't. Most gitlab releases don't introduce useful features, they mostly patch security issues and regressions. For example, the Runners are in a dire need of tons of features and an outright rework of some parts, but barely get any. Which is sad since they were so far ahead of the competition not so long ago.)