Ranked in these QuestionsQuestion Ranking
Pro Integration into GitLab
Good integration into the repository you build your docker images out of. Just activate it for your repo and you're done. Most of the time new projects/repo have it on by default.
Con Tight integration into GitLab
If you're not building your docker images via GitLab CI, it's kinda hard to push images to the registry.
Con Docker garbage collection
Gitlab has very poor docker garbage collection management by default. One must read a good portion of the documentation to know what to do, so that garbage collection kicks in.