Most folks don't realize that the Genesis was backwards compatible with the Master System. So the whole "Sony did it first isn't true." Hell the 7800 from Atari was backwards compatible with the 2600 in the late 80's.
Though for them to not offer BC shows that they just don't care.
I liked the PSP, but even with the 3000 series the PSP still was slow, and that UMD grind is really unsettling. There was a lot of good on the PSP, but the system itself to me didn't feel good, you know.
Total I think I owned about 25 PSP games. My most played was the remake of Mega Man X. The port for Parappa the Rapper was broken because they didn't change the timing for the game to match the refresh rate for LCDs. I own more DS games than I did PSP, by a small margin. I can keep my DS games though as they can be played on my 3DS. PSP games got no love on the Vita though unless you lived in Japan.