Am I gonna be the only one here who likes the PSP?
I had the same question about this a while ago, and despite many comments saying PSPs suck and what not, I went ahead and still bought one when the Entertainment Pack came out.
It's really good. I have three games for it right now: ATV, MLB 06 and NBA Ballers. The battery life is fairly decent and the games are fun to go around with. As for lagging load times, it depends on the game. For example, NBA Ballers takes 2 minutes or so to load while MLB 06 is about half of that. Loco Roco takes like 5 seconds. The Internet connection is quick and snazzy, and I can access a few points from my house, probably from a few neighbours as I don't have a router. I've been using it as an entertainment hub of sorts. I have a few movies and about 40 songs on my 1 gig stick, and it's really handy on road trips.
If I had a say, I'd tell you to go for it, especially if you get a good deal. And I do agree though in that UMD movies suck. They're pretty clear and all but it kills the battery life. Better to download/convert movies.