When it comes to the battle of these two super portables, to me it all comes down to the quality of the screen/screens.
I've been waiting a very long time for a handheld gaming system that has a really, really good screen. So far, other than the Zodiac, which I don't consider to be a real entry into the portable market, I haven't found a screen that I've totally liked.
The Nintendo GameBoy Advance SP screen is decent, but just not bright enough, and vivid enough for me.
Now, it appears as though the Sony PSP will have the superior screen. But the big downside with the PSP, is the fact that Sony is going to position this portable as a 3D machine. On the other hand, the Ninendo DS will do both 3D and 2D, and in many instances at the same freaking time! Since I'm a huge, huge fan of 2D, and not a big time fan of 3D, this makes things more complicated.
I love the fact that the Sony screen is so large, and also that it's widescreen 16:9. I also feel that it most likely is a very bright and crisp display, considering the price is likely to be $249.99 or so. No way you can charge over $149.99 for a portable and not have a truly kick ass screen.
With the Nintendo DS, because they are using "TWO" screens, that worries me a bit. I know that one of the screens is a touch screen, with a protective coating on it, but still, you have to imagine that with the cost of having two screens, that the quality of the actual screens arent going to be that great.
I've heard that the non touch screen display is a little bit more vivid and bright then the SP, but we shall have to wait and see.
So for me it basically boils down to this.
Sony PSP = A screen that I've always been dreaming of, but a focus on 3D next gen type gaming.
Nintendo DS = Two screens, one of which is slightly better than the SP, the other a touch screen, and a focus on both 2D and 3D gaming, with some classic Nintendo gaming thrown in for good measure.
It will definitely be interesting to watch both of these units actually arrive at retail, and see exactly what they really turn out to be. When it comes to portables, you really need to see the final incarnation of the product up close and personal, to get a real feeling for it. Pictures and video of the units just won't cut it as far as I'm concerned.
Oh, by the way, another huge factor will be emulation. Will you be able to play SNES and Genny games on the PSP? That would be sweet! Then I might just be willing to go the PSP route. It does have the better screen, at least I'm thinking it does, and I just want some 2D love. So if I can play all the classic 2D games on the PSP via emulation, then I would probably go that route.