I thought this was a great PSP article on kotaku via N4G. As documented here, my PSP ownership has been very hit or miss. My periods of PSP enjoyment are often followed by very long (as in months) dry spells where the PSP does not get any love.
Over the last few weeks that has changed. I really think that for the most part I have been playing the wrong games. Gems like Ratchet and Clank: Size Matters and God of War: Chains of Olympus are very worthwhile PSP gaming experiences.