It all depends on what you like: video game system that does 3D without the glasses that can do most and more than an overrated mp3 or an overrated overpriced mp3 player?
I'm a gamer, so if I were you I would get the 3DS because...
"The Nintendo 3DS is based on a custom Pica200 graphics processor from a Japanese start-up Digital Media Professionals (DMP). It has two screens; the top screen is a 3.53 in (90 mm) 5:3 3D screen with a resolution of 800×240 pixels (400×240 pixels per eye, WQVGA) that is able to produce an autostereoscopic three-dimensional effect (one without 3D glasses), while the bottom screen is a 3.02 in (77 mm) 4:3 non-3D touch panel with a resolution of 320×240 pixels (QVGA).
The system features several additions to the design of the original DS, including a slider on the side of the device that adjusts the intensity of the 3D effect, a round nub analog input called the "Slide Pad", an accelerometer, and a gyroscope. In addition, there is an infra-red communicator port situated on the top of the unit.
The 3DS has two cameras on the outside of the device, capable of taking 3D photos and capturing 3D video, as well as a camera positioned above the top screen on the inside of the device which faces the player, capable of taking 2D photos and capturing 2D video; all three cameras have a resolution of 640×480 pixels (0.3 megapixel). The system also has 3D movie playback capability; Nintendo has made deals with Warner Bros, Disney, and DreamWorks to deliver 3D movies. Although no titles have been announced yet, the trailers for DreamWorks' How to Train Your Dragon, Warner Bros' upcoming film Legend of the Guardians: The Owls of Ga'Hoole, and Disney’s upcoming film Tangled were shown on the 3DS during the Expo.
In addition to its own software, the Nintendo 3DS will be backward compatible with Nintendo DS software, including DSi software. Announced titles include Kid Icarus: Uprising and Mario Kart 3DS. Many companies have signed on to develop for the 3DS, and over 60 titles in all have been confirmed. At launch, the Nintendo 3DS cards will hold up to 2GB of game data and look almost exactly the same as those of the current DS. However, there is a small tab jutting out on the one side, most likely to prevent 3DS cards from being inserted in a Nintendo DS.
It was announced at the Nintendo of Japan press event on September 29, 2010 that the 3DS will have a Virtual Console Service with Game Boy, Game Boy Color, and "Classic Games" in 3D.
Multitasking is available on the 3DS (i.e. You can access web browser while in game).
Miis will be available on the system. There will be a new Mii Creator on 3DS with the ability to import from the Wii and create a Mii from a photo taken by one of the cameras. Miis can also be loaded by capturing special QR codes with one of the cameras. There also will be a 3DS Mii Plaza to house all the Miis you've seen in Tag Mode.
Several augmented reality games will be included on the 3DS with 6 paper cards that interact with the games.
The system supports multiplayer gameplay via a local wireless connection or over the Internet. Expanding upon the connectivity of the Nintendo DS, the Nintendo 3DS features an "always on" background connectivity system that current trademarks suggest the name being "CrossPass", which can automatically seek and connect to wireless network nodes such as Wi-Fi hotspots, sending and downloading information in the background while in sleep mode or while playing a game. One application being considered for Crosspass is functionality to "automatically acquire magazine and newspaper articles", similar to networked e-book reader applications. The background connectivity will be utilized in Crosspass, which allows users to exchange software content regardless of what software is currently in the console. For Crosspass, sharing content is stored in a "data slot" in the console. Using this data slot, Nintendo 3DS users can readily share and exchange content for multiple games at the same time, whenever they are connected, even when playing unrelated games. Using the console's background connectivity, a Nintendo 3DS in Crosspass Mode can automatically discover other 3DS units within range, establish a connection, and exchange content for mutually-played games, all transparently and without requiring any user input, even when the console is dormant. Crosspass Mode can be customized to fit the user's preferences, including opting out of Crosspass Mode for selected software. An included cradle allows for faster downloads and uploads, and will act as a charger." --Wikipedia
Other info on 3DS:
http://www.youtube.com/watch?v=GRSdUvbLhSo
Game line-up:
http://www.youtube.com/watch?v=AzOUHU5SKSA&feature=channel
And if you never had an mp3 player, then get iPod for now. But be aware that the 3DS also features a music player.