The problem I had with GitLab was that the mechanisms for controlling dependencies between stages were fairly basic. They only added them in ~2020 I think, and they weren't well documented.

Additionally, there's no cache guarantees between jobs within one execution. This means that you can't reliably cache an artifact in one job, and then share it with multiple downstream jobs. It mostly works, but it's hard to debug when it doesn't, especially if the cache artifact isn't versioned.

GitLab is "fine", and has some nice usability features for basic pipelines, but it's definitely not doing anything better than the other major providers with respect to these problems.