This, about the mental overhead. So much.
@Sarrah: I put some of my thoughts here: https://news.ycombinator.com/item?id=16214892
FWIW I agree with pretty much all of those points. Great to point out things like line length and container size.
Also possibly worth mentioning, I have the same problems with much of the marketing site and blog, not just the application.
It's not just an issue with merge requests or issues, it's more of a general thing – the colour palette and typography do not make GitLab easy to scan in the same way that GitHub is. I find it requires much more mental overhead to parse GitLab.