This is probably the most commonly held mis-conception regarding the PSP. That there aren't any "good" games.
http://www.gamerankings.com currently lists 234 titles available for the PSP, naturally they can't all be bad, right?
I tend to break down game ratings by grade level, 90% and above is an A, 80% and above is a B, etc. Pretty much any game that gets an A or a B is above average and is worth playing. Similarly anything scoring below 70% (D) or 60% (F) is below average and not worth playing.
Pretty simple, right? So look at the scores:
37 games score above average. Sure, gaming is a matter of personal taste, but that doesn't qualify as "no good games" by any stretch of the imagination. But how does this compare to the competition? The Nintendo DS?
The DS has been on the market a little bit longer than the PSP so you'd expect it would have more games. You'd be wrong. It has fewer games and fewer games in the "above average" category. But it's also incredibly "bottom heavy". A whopping 138/222 games simply aren't worth even considering. That's 62%!
Putting it another way... For every title worth playing on the DS Lite there are 4.18 titles that are pretty much garbage. The PSP may have quite a few bad games as well (119/234 or 51%), but that comes out to one good game for every 3.22 bad games.
In short, when comparing the Sony PSP to the Nintendo DS, the PSP has more games, better games and a more favorable ratio of good games to bad games.