A PSP is a fun handheld. Compared to it’s rival the Nintendo DS, its more powerful, the games look better, and they are arguably more adult orientated.
As a long time PSP owner here is my impression of its emulation quality.
Gameboy Advance: Good
Genesis: Poor. Lots of slowdowns. Sound is laggy or doesn’t sound right.
SNES: Poor. Lots of slowdowns. Sound is laggy or doesn’t sound right.
Playstation/PSX: Great, if not close to perfect. The PSX emulator on the PSP was written by Sony. The quality is outstanding.
GameCube and above: Nope
I see a lot of recommendations online to use a PSP as a cheap SNES emulator handheld. Don’t fall for that. The SNES emulation is bad. It’s so bad I don’t even keep the emulators or ROMs on my PSP. I have never played through a game. I couldn’t even make it through the first level of Contra 3 because the sound of my gun was so high pitched it was annoying me.
If you want to play some PSP or PSX games, definitely get it. You’ll never go wrong playing a game on the original hardware it was designed for. PSX emulation is great, in my opinion it’s better than the PC emulators.
The biggest downside to a PSP is the battery. Batteries don’t age well and the PSP is getting old. Official replacement batteries from Sony don’t exist. Aftermarket batteries are horror stories (check out some Amazon reviews). Most people either stay plugged in all of the time or use an external battery like you would use to charge your phone in an emergency. I read an article of one guy who removed the UMD drive and soldered in two NDS batteries in their place. I’m lucky enough that my battery is in good shape, but when the time comes for a new one I’m a bit worried.