Is it the battery?

The biggest flaw of the Surface Pro seems to be accepted as the battery.

So, ignoring the 'can't use it on my lap' argument - which is about as useful as complaining about the MBA's lack of a touchscreen - how different do you think the reviews would have been if the battery life was longer? Let's say equivalent to the industry leading 13" MBA?

What I'm asking is, is the battery life going to be the main issue for this and future generations of the Surface Pro? Is that where Microsoft should be concentrating their efforts, or is there something even more important for this hybrid to succeed?