IMO, some are over-reasonning in this topic
This : http://www.vgchartz.com/hwcomps.php?cons1=DS®1=All&cons2=PSP®2=All&cons3=DS®3=All
sums up my view.
DS vs PSP sales were driven essentailly by software realeases.
If you look closely to the first year, you will see that sales were fairly similar. It is on the first "real" holiday season, along with major software releases on DS (Brain Training, Nintendogs) that the gap started to really exist and widen.
By the time, other software releases (Pokemon, NSMB, ...) concurred to widen the gap.
Nobody can deny that no software on PSP had impacts similar that such titles.







