I own both a 3DS and an iPod Touch. Both are stable gaming platforms, but let's look at the facts:
iPod Touch:
Use Time: Between 1000-2000 Hours
Time of Ownership: August, 2010
Use: Music, Videos, Images, Games, and Social Networking.
Usage: Well, I'm now a high school student, so I'll be using it a lot more than before, but only for music and networking
Nintendo 3DS:
Use Time: Between 200-300 Hours
Time of Ownership: March, 2011
Use: Gaming, Music.
Usage: I LOVE Zelda and the Virtual Console, but the music isn't bad, and the 3DS has barely taken off!
Verdict: Nintendo 3DS
I use my iPod a lot more, but why? Music, and why not the 3DS music? Because the iPod is thinner. Despite the fact that it's fun to hack, the iPod doesn't have a lot of stuff to offer other than "Hey, let's get on facebook, download a free app, and maybe watch a movie!". The 3DS is a very dedicated system, which I believe hasn't really taken off. Zelda, Mario, Kid Icarus, Pokemon, Metroid, Star Fox, and MUCH MORE! Granted, they have lowered the price, but we haven't seen anything yet with Nintendo. They alwasy have something in store for all the haters to hate on. End of story.