I don't own a PSP but the constant complaint I hear from people who own a PSP (and often a DS aswell) is that the PSP offers very few games which are really appropriate for a portable system, and very few games which are drastically different from what you can get on a home console.
I can't speak for everyone but I know there are a lot of handheld gamers like my sister (32 years old) who moved to handheld gaming with the Gameboy Color because systems like the Playstation and N64 stopped offering the types of games she enjoyed playing. There are also a lot of portable gamers who want games that can (easily) be played in 5 or 10 minute bursts.
I could be wrong but the PSP's library seems pretty good for a home console system but misses why a lot of people owned portable systems in the first place. As such, I don't believe that it is appropriate to try to line up the system's games via genre to see which is the better portable system.
