Well obviously a 2 year old isn't capable of playing anything other than simple straight forward games. 5 year olds probably still lack a lot of skills needed for more complex gaming (or more complex tasks too for that matter) too.
If it's easy enough for a 5 year old to play it, it's easy enough for any casual gamer. BTW, my 5 year old primarily plays tower defense games and physics oriented games.
Yes. Its a phone. Besides if you look at the metro's the amount of iphones you see is nothing compared to the amount of other phones. Also its far far smaller than the amount of people with a ds/psp you see and if you consider that a fair amount of people probably does little to no gaming on their iphone I don't see how apple is a threat to Nintendo. Sure apple sells games, but its on a different level than Nintendo. Apple is for the small, im bored and want to be entertained for 5 minutes games. Nintendo (and sony) are there for people who want bigger games. Even a simple pick up and play game like new super mario bros already has way more depth than any iphone game I ever seen.
Apple has sold over 50 million iPhones, has 200,000 apps in the App store and sold 1 billion apps (or about 800 million games). Games are cheaper to develop for iPhone/iPad and you have a superior distribution channel. If you can't see this as a threat, you're too blinded by loyalty. Have you even looked at the iPhone store recently? Grand Theft Auto is on the iPhone. You think that's a casual 5 minute game? EA, Activision, all the heavy hitters are plowing resources into mobile.
The newest iPhone even has superior motion controls to the WiiMote. Like I said, I own a DS, but I don't take it on flights any more, I take my phones and iPad. If I get bored of a game, I just download a new one, any time, anywhere. My DS is sitting on the shelf collecting dust now.
All this, and I personally *hate* Apple, but they are making some damn good products with excellent user experience.
My prediction: In mobile, Nintendo is heading the route of Sega. In 5 years, they'll be making software for other company's mobile HW.