When I recently asked about them in a Game Stop, I was told to wait for a new 2DS to come out before buying. Supposedly, the "new" 3DS has new internals and new games coming out will only be compatible with the new systems. The old games will still be playable on the new stuff, but new games won't work on older versions. My 11yo son said he would choose the iPhone/iPad over a DS (he has an older DS XL and my old iPhone that doesn't have cell service). His reasons (All of these apply to the iPad as well): There are a lot of free games available for the iPhone. The games you buy are much cheaper on iPhone.
He likes the games on the iPhone because there is more variety. They have all kinds of games like physics puzzles, room escapes, and digital versions of board games (Pandemic, Catan, Carcassonne, Agricola, Eclipse, Tigris & Euphrates, Dominant Species, Through the Ages, etc) that are not available on the DS. The iPhone is much more versatile. He uses a pomodoro program when doing school work to track his time; he has a sports app that gives him alerts about the Red Sox games; he uses it for his Bible; he has a weather app on it that he likes to use; and he likes to use it to be able to text us when we are away working (we are photographers).