Summary: Bought for my PSP-2000 in 2010 and haven't had a single issue. Never did a real comparison with the Sony MS Pro Duo—partially because the one that came with my system was a scant 32MB. (Thanks, Sony...) But IIRC, it seemed ever-so-slightly slower.
Summary: I bought two of these, one for psp and one for camera. They are both doing great after the few months of use. I had an 8GB stick from Sony and it died after two weeks of use. It lost it's formatting and my wife lost 2GB of pictures. Not good. Luckily we back up constantly.
Pros: It works and its quick. It formatted when I put it in my camera and I didn't have any issues at all. Plus for 23.99 when I bought them was a steal.
Pros: Sony claims there play station line only does everything with this much memory my PSP can now store tons of music, videos, pictures, games and more now I truly can use my PSP for anything without the bother of carrying and changing multiple memory sticks
Cons: My PSP's boot time has become noticeably longer but not so much so that it is bothersome or a problem. good things come to those that are patient any how.