Have you made websites recently?
I do not mean to sound critical about you personally? I wrote a kind of bad trollish review below. With that ouf of the way IE 11 is one of the most standard compliant browsers available. It does not support the most features but it supports those correctly. Webkit/blink is the worst. CSS 3 animations is like IE 6 you need hack after hack of -webkit to get it to work.
Why is it we accept Google doing this yet bash IE 6 as the anti Christ when it did the same in 2001? Spartan is a better browser than IE 11 but Chrome and Mozilla accelerating in the last year faster than the project Spartan could catch. So in a sense it is about Chrome in 2012/2013 but with more standards compliant. It still is beta in a rewrite engine stage so I won't bruise MS too much more on this
After the new engine stabilizes they need to add quite a few features like interactive forms, pointer events, drawing primitives, stencil support in webgl, to catch up to the other browsers. However I do not know if the W3C standardized these yet.
Since IE users NEVER EVER UPGRADE the last thing MS wants is to implement a changed feature later on and be stuck for the next 10 years where developers curse them for writing 2 versions of that standard after W3C changes the final spec. This is what happened with IE 6 besides the bugs. CSS 2.1 was very very new and changed final after IE 6 came out. firefox implemented it the other way causing 2 rifts as it was assumed users and corporations would upgrade to IE 7 FAST and quickly. We all know they never happened and kept the damn IE 6 until 2011.