The article doesn't answer an obvious question -- whether an Eclipse-based Android project can be seamlessly imported into Android Studio. That was the first thing I thought of, and in scanning the article I saw it wasn't addressed. IMHO a glaring omission.
EDIT: The Google article about Android Studio covers this -- it's a two-step process in which one exports a project from Eclipse, then imports that into the new environment.
I've tried it for a simple project and it worked flawlessly. The new build system is quite well developed at this point, so most developers should be able to get their app building on it. It's not 100% complete or 100% bug-free yet though - for a mature app you might want to wait until it's out of beta.
EDIT: The Google article about Android Studio covers this -- it's a two-step process in which one exports a project from Eclipse, then imports that into the new environment.