User research shows a pretty negative experience with findability and usability and hamburger and suggests sacrificing screen real estate for discoverability, based on basic human memory and attention issues. There are pros and cons.

One site did an A/B test with a hamburger menu on mobile vs. the bordered word "Menu". "The MENU button was clicked by 20% more unique visitors than the HAMBURGER button". Though when compared iOS vs Android they found "Android users are almost 3x less likely to click a navigation button than iOS users", which speaks to concerns about hiding the navigation at all.