HATE: IE Lock-In
Internet Explorer 10 is actually not a terrible browser. We still prefer others, but when used in full-screen mode on a tablet, IE10 is so well integrated with Windows 8 that it's hard to find fault with it. But, there was one thing to hate. If you're using an app that calls upon the system's default browser to display, let's say, some help pages, the only browser to work properly in our tests was IE.
We came across this by accident, but we observed and were able to repeat the behavior by attempting to access the default browser from within more than one app. The function worked every time with IE as the default, but failed otherwise. To its credit, Microsoft presents a list of the browsers installed on the system when any browser asks to become the default.