I have run Windows 8.1 for a couple of weeks now. One of the news in Windows 8.1 is Internet Explorer 11. I have not used Internet Explorer as my main browser, but of course I wanted to try it out.
You also get help to see if elements are in line when you selecting an element (see image below). I think that could be a very helpful tool.
The only thing that I miss is that I can nott set Internet Explorer in compability view. When working for a customer that use older versions of Internet Explorer is has been a very good feature to change document mode. When using Internet Explorer 11 I need to use a virtual machine to test websites on other browser versions than 11. Microsoft links to a tool that is called Browser Stack. I signed up for a evaluation account, but it dosen't work well, it was lagging so it was very hard to do the testing.