This should come as no surprise to PSP owners, but it's interesting to see the numbers nonetheless. When looking through the ESRB database, one sees that the PSP offers a greater variety of games than Nintendo's handheld. The PSP features 30 titles with an M rating. The DS, on the other hand, only has 2.
Teen-rated games also find their home on the PSP. The DS only has 31 Teen-rated games, while the PSP has three times the number of titles, with 96 T-rated games.
While it's undeniable that the DS is selling better than the PSP, one has to wonder how many of those consoles are for adults. I'd assume not too many. Grand Theft Auto sold over a million copies on Sony's handheld, while LocoRoco went by mostly unnoticed. I think it should be pretty clear that the two portables are targeting two very different markets: and older gamers, like myself, enjoy the slightly more adult-themed games of the PSP.