The text-combine-horizontal property from CSS Writing-Modes is now recognised with the -ms- prefix. However, I’m not sure to get this to work. I assume it only works with glyphs that are upright in vertical text, but IE doesn’t support the text-orientation property. Perhaps this is work in progress?
The big news with IE11 is that WebGL is supported and enabled. Despite IE getting a lot of flack for not supporting WebGL, it looks like it beat Apple to the punch. WebGL is disabled by default in Safari.
Some new features of Canvas 2D Level 2 have been added, including image smoothing, the even-odd fill rule, and dashed lines.
IE 11 supports the MPEG Dash (Dynamic Adaptive Streaming over HTTP).
SPDY/3 is now supported. I was expecting it to be branded as HTTP 2, but this is not the case so far.
More of IE11 is hardware accelerated, using DirectX 9
Previous pages are cached for near instantaneous flipping through your browser history
Pages are prefetched and pre rendered (like Chrome) for faster page loads (if the browser guesses right)
There are further live style sizes and further capabilities for what you can include in a live tile.
Numbers in a web page can have click to call enabled. I don’t know if this is just done by heuristics, or if you can add something special to the markup.
Test scores have to be taken with a huge bucket of salt, as they just cover a subset of features (for example HTML5 test doesn’t include many of the APIs above, and CSS3 test doesn’t cover CSS2.1, CSS Level 4, or many of the specs supported by IE like Grids, Regions, and Exclusions), and are sometimes incorrect (WebKit incorrectly parses things it doesn’t support like background-repeat). With that said, this is how IE11 preview performs on various popular tests: