First glitch faced in experimental Internet Explorer 11 today was due to User Agent. Few of Web Apps on HCL are still does not work without IE. and you know that new Internet Explorer 11 have different User Agent so that old IE related hacks does not get applied to new IE as the new IE comply mostly with web standards so it does not need those 'special' treatment.
I got a Addon called "UAPick User-Agent Switcher" which worked on IE11. Thanks God that it works in new version of IE. User agent of IE11 is "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko" which does not have MSIE in it which was used to detect whether it is IE browser or not. So, I thought to change the user agent to old style user agent to give those applications a try and it has worked. At least those applications have not given me error that this application does not work without IE. One application that is Microsoft's one is working but not as earlier. That application is Outlook Web App. I remember when I used to right click on Inbox etc link on left side then it used to give me shortcut menu but even after changing user agent to old one it has given browser property menus. But it is fine as I can work with it.
I can say that IE11 is working perfectly except that it does not get recognized as IE itself. In that cases where Web Applications are meant to work only with IE need to make adjustment otherwise those users need to install User Agent Switcher Addon like I need to do.
Update(26 Aug): It would be very daring steps for Microsoft to push the IE11 into market. I need to downgrade back to IE10 as part of my company's portal was not working which is made mostly for IE browser. You may need this page for uninstalling IE11. Good part here is no need of downloading IE10 again.