I have to use GitLab for work and I find the UI much harder to use than GitHub, so I agree there. But, it's open source and we can all contribute, and in particular the best place to make your feelings know about the UI is constructively in the issue tracker.
Here's the main issue sparked from the last HN discussion about GitLab UI: https://gitlab.com/gitlab-org/gitlab-ce/issues/25752
This actually makes you the perfect candidate for giving us good feedback. You may not be able to articulate exactly why UI elements feel off or don't work for you, but you know they could be better. If you are interested, you can join our UX Research Panel to help us pinpoint areas we can improve. We want you to love GitLab too :)
Only on gitlab.com, on prem here it flies.
Yes it's rude, but I want to love GitLab - it's amazing. However I just can't bring myself over with this UI. It's just too bad and too unintuitive. Also slow.