I use Ubuntu as my sole OS too, but it gets on my nerves with some things. I have cmd+E mapped to a new nautilus window, for example, and it doesn't work half the time (I always have to press it twice). Sometimes the focus gets lost and alt+tab won't work until I click on a window. It's also not very responsive.

Windows, on the other hand, are extremely snappy everywhere. Pressing cmd+E immediately launches Explorer and Explorer itself is very snappy.

I wish Ubuntu would just get its shit together and address UI latency at some point.