I bought the PSP a couple of weeks ago. Got it from someone is Japan and it cost £200 for the value pack and also included Ridge Racer and a screen protector. If someone is thinking of buying one then get a screen protector with it as otherwise it'll get scratched. The system itself is awesome. I have only got RR at the moment but the graphics and gameplay are awesome. The graphics are are on a par with PS2.
My machine doesn't have any dead pixels, but i have read elsewhere that some people have suffered with this problem.
Is is better than the DS? In my opinion it is but I guess in the end it comes down to personal preference. If you are a fan of the nintendo games such as "mario" etc then the DS is for you, if you want a machine which delivers unbelievable graphics, mp3 playback and UMD movies then go for the PSP.