I am not a heavy LaTeX user but I do write about mathematics every now and then, and I find MathJax extremely useful. I have been using it for the last 2 or 3 years – no issues whatsoever. It simply works, both on PC an on mobile. The biggest selling point to me is that it allows for selecting & copying math expressions as text (as opposite to other LaTeX plugins that convert expressions to png). This makes things scalable, performant etc. Good work!