Yes.
But do you think graphics matter that much? I ask because it seems like that's what you're inferring. The PSP has better graphics, hands down, and it can run 3D games better than the DS. However, if power was the biggest factor in success, the PS2 would have lost to the XBOX long ago. IMO.
The thing though is that it's about the games. The PS2's strength is its huge library. Not only does it have a ton of games, but it also covers almost every genre. The same is true of the GBA. Not the best graphics in the world by any means, but it has a huge library of games.
As far as numbers of games and variety of genres go, I think things will be even between the two, although the touch screen on the DS allows for some games that can't be done on the PSP (Feel the Magic, that surgery game, Yoshi's Touch & Go, etc).
Basically, I think the DS games will be more fun. There's just something really cool about having that touch screen.