I'm always glad to see people experimenting with different approaches to building and deploying apps. That said, the general idea of this Serverfree approach doesn't appeal to me. On any given day, I'll use 4 different devices. I need my data to synchronize seamlessly. I wouldn't use a program (in-browser or traditionally installed application) unless I can synchronize that data either by storing files in a Dropbox-like program or in the cloud. I don't want to have to remember which computer/browser combination I was working on.
Edit: forgot some words