Been a Nintendo fan forever, bought all their hardware, even the virtual boy. One thing people don't know about Nintendo is that their first party games have annually outsold the top third party (usually EA or Activision). Combined sales for all platforms, not just on Nintendo hardware. This is quite impressive considering that Nintendo first party games can only be played on Nintendo hardware.
That's going to change this year since we're eight months in and they really don't have a hit, 3DS isn't doing so hot, and vanilla DS&Wii are significantly winding down.
The thing about Nintendo handhelds is that they've carried the company during the worst of times. When virtual boy flopped and n64 failed to be a hit in Japan (also had a rough time with 3rd parties), the gameboy pocket and Pokemon saved the day and led to the gameboy color which sold quite well despite being significantly antiquated even then. When the Gamecube wasn't selling so well, Gameboy Advance sales made up for it.
Nintendo's handheld dominance hit it's highest point with the DS. Many gamers expected the 3DS to repeat this success despite skepticism from analysts because of smart phones. I bought a 3DS and immediately had buyer's remorse. (I also consider myself a core gamer)
Core gamers do not want to admit the reality that the playing field has changed. iOS is a contender. I realized this during a four hour plane trip after being too lazy to get the PSP from my carry on in favor of gaming on my iPhone. There are several high quality full length games. You can get use to touch control. Normally you always have your phone with you (most people, especially adults, aren't going to lug around a DS everywhere they go).
iOS can and will do better as more people realize this. I was in denial for a while myself. The type of casual and mini games that made DS a success can all be played on iOS without a stylus and with multi touch. What I didn't like about the 3DS was that the resolution was low, lower than a PSP. My retina display has spoiled me. I prefer it over the gimmicky 3d effect (which has ghosting btw and a slight turn of the device when using gyro controls will kill the effect as will pulling off SSF4 moves).
I'll use an example, Ridge Racer. I know Ridge Racer isn't Gran Turismo or Real Racing 2 for that matter, but I enjoy it. On PSP it ran at 60fps and on 3DS it runs 30fps with a lower poly count (but better lighting). Now the iOS version was based of the PSP version and was disappointing at first but surprisingly Namco updated it with more tracks, a better framerate, improved controls, and RETINA support. The 3DS version cannot compete, I wound up selling it.
Sorry for the tl;dr, what I'm trying to say is I would love to have Nintendo games on my iPhone. Even a retina port of Mario Kart DS with game center support (and fixed snaking) would be amazing. I'd pay $15 for it.
Ridge Racer Accelerated (iPhone version, retina display updated earlier this year)
Ridge Racer PSP (released in late 2004)
Ridge Racer 3DS (release earlier this year)
Ridge Racer Accelerated is based off the PSP version. It originally ran slow and to my eyes looked like the resolution was lower than the native 3GS display. It's been updated to include more tracks, improved controls, game center achievements, and retina display. It also now runs 30-60fps (PSP version ran at 60). Ridge Racer 3DS runs at 30fps and the HUD is generic and 16-bit looking. It does have more tracks (15 vs 11 on iPhone). Still, the 3DS version is $30 and the iPhone version is $12 with all the DLC. The iPad verison is freemium.