Hiding the main menu within a hamburger or similar is relatively commonplace on the web these days. You generally see it on modern sites or sites that are targeting a younger demographic.
The question is, does hiding the menu degrade the user experience? I get asked this question regularly, and my answer is, it doesn't hurt UX at all. We've had enough exposure to this concept that I believe that most users will grasp this kind of functionality.
When I did a quick search on the internet for opinions, I didn't find much, but I did get a sense that people are split 50/50. What I did discover was this study, which was written in 2016.
The benefits of hiding the menu are purely aesthetic. It's also important to note that if you were to hide the menu in any sort of way you should provide alternatives for navigation, for instance, placing top tier pages as links in the footer and linking to content via the body.
So, Yay? or Nay?