The move to a hamburger menu saw significant outcry, and was followed by one of the more popular tickets I've ever seen on GitLab asking for the ability to restore the menu pin feature. Every complaint and criticism was basically replied with "Nah, we're keeping it.", because the new hamburger menu had gone through "design testing".
If you're looking to improve UI/UX, the design team should look through those tickets and learn how to listen when so many users are speaking up against a redesign.
Rest assured, that we are hard at work at this (see for more information https://gitlab.com/gitlab-org/gitlab-ce/issues/32794). Even better, if I am correct, there will be a new navigation concept (first alpha iteration) released in 9.4! This will be hidden in a feature flag, which will be accessible from your personal settings.
In the coming months (and thus releases, every 22nd!) we will continue to improve upon this concept, to eventually enable it by default for everyone to enjoy.
We know that the shortcomings of the hamburger icon are suboptimal, but also know that reverting is not always the correct choice. With the new navigation concept we focus on getting a clear distinction between global and contextual navigation. We did proper UX testing to be able to clear out multiple bumps in the road/implementation and are pretty stoked about finally getting it in!
Again check for more information this issue https://gitlab.com/gitlab-org/gitlab-ce/issues/32794. The scope of revising navigation is pretty far reaching and has been on the minds of almost everyone on gitlab!
Note that colors, functionality and any specifics can change throughout the process of implementing over the coming months :)