Everyone is waiting for the pro version to come out...why buy this one?
I mean, let's look at it this way - 50% thicker than the iPad and Surface RT. Nearly 40% heavier than the RT and iPad. Substantially poorer battery life (estimates are between 5-6h as opposed to the 9-10h demonstrated on the RT and iPad). Runs so hot that it needs to put a spinning fan in your hands.
The Pro is strictly a niche device. If the RT isn't doing well the Pro sure as hell isn't going to save it.
Fitting that into a Surface like size will not be easy unless we see a component or platform that is yet to be introduced.