It looks pretty clean. It should appeal to the people who were buying Nokia's Harmattan and Meego devices. If Jolla can pick up a majority of the Qt apps that had been developed for those platforms and grow that developer community, they may have a chance.
It will take at least a year, and probably some more hardware to tell where Jolla is going and if it will be successful. There are several dimensions to measure that success: Can Jolla pick up many of the distribution channels, and their customers, in Europe that previously favored Nokia? Can they penetrate the China market, as they appear to be aiming to do?