It never had a spectacular game that wowed me (Although it certainly had games that did that for many people, such as the Monster Hunter franchise in Japan and the God of War franchise for many other gamers; I just never encountered something like Ocarina of Time was for me on the Nintendo 64).
But I'm glad I've owned a PSP. It had a solid library of good games that I've enjoyed playing over the years. I'll be enjoying it for years to come and might still stumble across that game that reaches the A+ mark for me personally that I've yet to encounter.
My biggest regret with the system is the lousy analog nub design that they used. If they had just gone with something better, my enjoyment of the PSP would've benefited greatly. I didn't mind the lack of double analog control nearly as much as I did that the single analog nub that was there just wasn't very good. And on my 1000, the d-pad wasn't a heck of a lot better than the analog nub (Thankfully that was remedied at least on later revisions).
My 1000 doesn't get much use these days, but my 3000 regularly is used for my UMD collection and I'm playing various PSP downloads frequently on my Go hooked up to my television with my old SixAxis PS3 controller.
I always felt this like was exagerrated. While I'm sure a healthy number of people purchased one with emulation in mind, I'd be shocked to find out that the percentage of PSP owners that bought it for emulation purposes came anywhere close to even approaching 1% of the systems sold.
The average PSP owner wasn't even aware that the system could be hacked, let alone that you could install emulators on it. And most of those that did hack the system did it with piracy of PSP software in mind, not because they could do something like fire up a NES emulator on it.
It possibly might even be above the Game Boy and in 6th place. The 118.69 million figure from Nintendo that is commonly cited combined the sales of both the Game Boy and Game Boy Color.