GL is not browsable with JavaScript disabled while GH is.
It's very easy to deploy, consumes few resources (you can run it on a low-end VPS). It even has Jenkins integration.
However I don't know how it scales to big teams and projects since I only use it for myself. And I'm not entirely convinced by its security track record, but it looks like things are improving.
It makes the modern web so much more pleasant, paradoxically by breaking it, now that user-hostile machinations are the norm.
And yes, gitlab's web interface is substantially more annoying than github, in my experience.