This is absolutely a NIGHTMARE for new developers. People come into the language, and there are what seems like an infinite number of "the only right" ways to do something, all of vary degrees of complexity/usefulness, and all claiming that they are god's gift to computer science. That last part is the part that is most frustrating to me, and it isn't unique to javascript. Google, facebook, yahoo, etc. have all gotte…
It supports IE (back to 6 believe it or not), is backwards compatible with itself, is relatively mature, very stable, performs fine, supports modern stuff like component orientated architectures and custom tags (if you want them), interops brilliant with lo-dash/jquery and grows with you, it's also way more of a library rather than a framework so there is very little koolaid, the devs answer on github and are active (if not a huge community).
I also rather like it's Do The Thing binding syntax (not least because with phpstorm and pycharm you can create custom language injections on XML attributes meaning I can do jump to definition near perfectly).