To be perfectly honest, I don't see many 12yr old girls asking for a PSP and Medal of Honour for their birthdays this year.
Also, the PSP is more like a hyped GBA than a DS.
DS;
- Improved Interactivity; Touch Screen.
- More fun games aimed at a larger target audience. So there's always going to be more people buying it.
- Sleeker, "prettier" design, also available in Pink. XD
- Always been cheaper than the PSP, has more features.
- Compatible with the Wii.
- Backwards compatibility means even more games for the system.
PSP has
- Interactivity like a GBA.
- 360 degree analog thingy.
- Better graphics (I haven't seen it often, but aren't the 64-bit graphics in the NDS and PSP the same?)
- Looks like a GBA only more modern.