There are good games on every system. Whether there are enough that appeal to a lot of people or that overcome the system's other faults is another matter. Saying that a user can go buy extra stuff to fix the PSP's many glaring flaws as a gaming machine -- load times, battery life, size, delicacy, memory requirement -- isn't really relevant since that just drives up the price further when the DSL already has all those things covered for cheaper and has its own library of great games.
If you play a LOT and have money to burn then buying both is a great combo clearly but if you pick one most people are picking the DS because of the overall gaming experience. The PSP's multimedia functions don't help it be a better gaming machine. PSP is a good handheld, the DS is just better.
