We use gitlab at work, and I have to say that it is disappointing. The UI is so complicated to do the simplest things (e.g. to approve a MR you need to click a button that is actually a menu; the diffs are difficult to read; the 'To-do list' includes MRs that were already merged (how is that actionable?)) and it seems that they're struggling to turn around improvements quickly. The issue around the 'To-do list' including MRs that were already merged was raised years ago.
I also have to say that I'm surprised about the backlash against bitbucket. I find the UI incredibly simple and clear, as do all of the new joiners. With Script Runner you can do some pretty amazing things. It handles the huge repo's well too.
