I find myself using the PSP less for games and more for other stuff. I read your thread here first on the PSP, in fact. I was sitting with my 6-year-old upstairs, away from my computer. I started to reply, but text entry on a PSP sucks. (The whole reply would have been something like: "I'm on a PSP now. Like it OK, but good games scarce.")
As iPPi said, the really good games are very scarce. There are some. That Golf game you mentioned wouldn't be Hot Shots by any chance? I have that too, and it's very good for what it is. Loco Roco is a nice little gem. There's Lumines, of course. There are good versions of some console games, which look nice and move nicely (including a Katamari game--yay). But the problem is that control is nowhere near as good as with a Dual Shock controller. The analog nub on the PSP stinks. 3D first- or third-person games suffer.
The little system does do well with passive media (movies, mainly). UMD movies are too expensive, and that's a shame, but the saving grace is that you can encode them from DVDs into MP4s. With a little effort, they can look pretty good too. The PSP screen looks terrific. The low refresh rate will cause some artifacting (looks like a color bleed on edges during motion). But overall, it beats the competition's resoundingly. Very nice for watching stuff on the go, or in bed. The sound quality is good too, through the headphone port. The built-in speakers are surprisingly bad (even for a portable).
Then there's the whole homebrew scene (independently created software), but Sony being who they are try very hard and very often to shut that down. You need to choose between UMD games and homebrew in your choice of firmware. Newer games require newer firmware, and anything past 2.71 has no kernel mode (which makes it very tough to trick the system into running stuff like emulators). 1.5 is the last version which runs non-Sony stuff without a hitch.
I don't know what all your intentions are for a PSP purchase. What I said about it I think covers its utility. (I only touched on net capabilities briefly. Besides the limited internet browser, I've done audio RSS, downloading of MP4s, music and html content.) I'm happy I have it now, but I bought it for the gaming scene initially, and it has not delivered on that promise as it should have.
