They say they're cross-browser, but their examples extensively use -webkit- css properties without the corresponding -moz-, -o- or the "vanilla" versions. None of the page transition examples work in opera.
Regarding mobile browser market share: It is a common misconception that mobile browsers not based on webkit have a negligible market share. Look at this. http://gs.statcounter.com/#mobile_browser-ww-monthly-201010-...