I find the comparison that some people make between the iPhone/Android Smartphones and handheld gaming consoles very odd. The former is great for playing a relatively poorer quality game for a shorter amount of time but the latter, because they're designed to specifically play games and only play games, are better suited for longer gaming sessions.
You'd be very hard pressed to find a game on a mobile phone that'll have you putting in hours and hours of time playing...that's why the games are as cheap as chips.
As for the battery issue I can't see it being a problem. I've got an HTC Desire HD and the battery life is equally as 'poor'. Note the quotes...we've been spoilt in terms of the length of battery life for the DS. 3 hours of constant use before needing a recharge is quite acceptible these days. My Desire HD is always plugged in and charging when I'm not out and about and with the 3DS charging cradle the 3DS will be in the same boat.
Anyone doubting that the sales of the 3DS will eclipse that of the iPhone/iPad needs to seriously have his bumps felt.
Unless the NGP retails at a cheaper price than the 3DS you'll probably see the 3DS with a similarly ridiculous marketshare this gen. 70/30 give or take a few percent.
