It does not work for me personally. I don't like the way that the options appear in places that I did not predict they would appear in. When I interact with anything, I want it to behave exactly the way I expect it to behave, and to do so consistently.

The songza site does not behave as I expect it to, and even after I learn how it works, it does not behave consistently in its own mould. I click an item and up pops some 4 arrow thing. When I move over some arrows, yet more things pop up and on some other arrows, more things don't pop up, and there is no hint as to which will cause things to pop up or not. So even though one might learn how such a navigation works on that particular site, as soon as you go to another site, you will have to relearn again which of those arrows will cause popups and which will not. Contrast that to a right click menu which always indicates which options will pop out.

I don't think circles are good navigation tools, for the reason that there are very few popular tools which use circles as their main navigation mode.