considering external battery pack adds 10hrs (for a total of 13 to 15 hrs) to battery life, i'd say there's no problem there.
pricing will likely be $49.99, but $39.99 would be ideal, not to mention the bundled PS3Vita games which i can see going for $59-$79.
hopefully the apps will be cost effective as well.
i think Sony's approach to Vita is sound even with some hardware choices i don't agree with, but there support for garage and indie dev's is a step in the right direction.
digital distrabution will likely be big on Vita in 1 part considering games that don't get localized will available via download so the only question thre would be pricing.