in fact unity is a better one. it'll take time for the people to get adopted to such an interface which is often found in portable devices. and i think, in future most of the operating systems would spot such an interface for the users.but as far as a beginner is concerned the unity desktop provides a bit confusing environment, as you cannot find anything that easily as in earlier versions of ubuntu. for the users who are not comfortable with the unity, ubuntu provides an option for changing it to the classic GNOME. and i think, the unity interface wont affect the popularity of ubuntu.