I've tried using MS-only products for about a year before surrendering and switching back to Google.
Bing, Outlook.com, Windows 8.1/Windows Phone 8, Office 2013, all that sorts of stuff. Did not work out, and the biggest complaints about IE are:
1) Website compatibility. For some reason IE 11 chooses legacy mode for many modern sites like endomondo.com etc. which disables features and breaks stuff. Additionally, MS tried to force developers to stop using IE versions when determining supported features, which broke browser detection on many sites, including Google, banking sites etc. Basically they told "sorry, we don't understand your browser type" and gave an HTML-only interface or even no access at all. This may be a webmaster problem, but MS should have at least provided an option to enable user-agent spoofing by default. Now you have to press F12 every time you open the same website because IE cannot remember previous compatibility settings. The only option is to force "compatibility mode" for sites which is IE6 quirks emulation - totally stupid.
Plugin development for IE is much more difficult than other browsers, period. This means many small, simple (but niche) addons will never be done because you have to learn a lot in order to create even a simplest plugin.
Also, IE's search feature is terrible compared to Firefox/Chrome/Opera. No keywords for search engines, no option for adding search engines besides http://www.iegallery.com/ (does not have search plugins for all websites).
3) Privacy - for some reason Chrome is considered to be worse than IE. However unlike Chrome or Firefox IE has non-existing cookie management. In Chrome or Firefox I can only enable cookies for a pre-approved site list, while IE's only option is to clear all cookies.
4) Features - for many features IE hasn't changed much since IE4. Bookmarks are still stored as *.url files (no duplicates, no sorting, no support for characters like *,/,:). No spellcheck. Bookmark sync only works with Windows 8.
5) Stability - even though IE11 is faster and more stable than IE7/8, it still locks up more frequently than Chrome (but uses less RAM).
6) Updates - IE is terribly slow to update (once every 2-3 years???). And still updates require a system restart!
The only noticeable improvement between IE11 and IE7 is with speed, rendering and standards support. This may be good enough to make IE bearable on public or company-owned computers, but is not sufficient to switch Firefox/Chrome users back to IE.