"Modern" IE that doesn't support WebRTC, HSTS, and the most behind in supporting HTML5 features [1]. If that's "modern", I'd hate to see how their "non-modern" products look.
Not many sites use HSTS yet. IE says they'll support it in the next version anyway. For everything else you mentioned, they're right on par with Safari, which is not bad.
[1] - http://html5test.com/results/desktop.html