Right up front, I’ll say that I don’t mind the hamburger icon. Its use should, ideally, be accompanied by descriptive text– (e.g. “menu” ) in the interest of perceived affordance, and it should, to my mind, be reserved for mobile. For some reason, finding the hamburger icon in desktop views bugs me. True, it shields the viewer from the dread list of links that may offend a designers elevated craving for white space.
But the hamburger icon in desktop scenarios unnecessarily places one more click in-between the user and thing he or she wants to find. Usability is design too, right?
Evolution of a language provides usage as a determinant of the longevity of a word. A word heavily used, eventually makes it into the dictionary. As an indicator of a hidden navigation menu, the hamburger icon may, in time, attain universal recognition. Meanwhile, many users today still have trouble understanding native form fields, combo boxes and buttons, not to mention inspired, arbitrary, sets of icons and “buttons”.
Extra pickle, please
Sometimes, one hamburger isn’t enough. This was a new one on me: the double hamburger!

Not to harsh on this website at all; they’ve got needs. (One icon is ever-present and serves, I think, as a client portal. The other, is for mobile view.) Are two better than one? Could there be another, less rhyming solution? Likely, yes.
Agreeable though I may be to the hamburger, rather than going double, I’d perhaps stick to good ol’ hyperlinked text, “Client login”.
Like most web design and development decisions— it depends.