I've been at companies where I've tried (and failed) to convince other developers/higher ups that something like automatically creating an instance of an app based on the feature branch (what Gitlab/others are calling a "review-app"), is the best way to test individual features with high velocity (of course, this requires one more integration level test in the staging environment to make sure everything works together well). I'm impressed/awed/grateful that Gitlab is pulling these features into their 100% open source solution.
The most common complaints against gitlab are:
- Gitlab's UI is bad-ish (this is what made me consider going to work there/contributing and helping fix that)
- Gitlab is slow
And I think they're dumb. If you think UI on your code hosting tool and slow file operations (on the order of minutes, not hours) to be what would slow their org down, instead of the fact that you haven't automated things that Gitlab wants to automate for free for you (like test deployments actual deployments, build steps), in one coherent place (no juggling github, jenkins, jira, whatever else) then I think you're wrong.