Hey Dave.
I looked into getting one as well. I went off the idea because I didn't think that i'd get much use out of it. It's ideal for long journeys and things like that, but I don't do much travelling at the moment. And I don't think i'd play it at home becuase I already have a PS2 and a PC to play games on. But that's the only negative thing I have to say about it, and that's not even a problem with the device itself.
However they're really good. A few mates of mine have them and I was quite impressed. They're fairly pricey though, but if you think about it you're getting 3 things in one. Games, Video, and an MP3. There are a few games that take my fancy, GTA: Liberty City Stories for one. It has a multi player function which I think is very appealing.
The suppose the main issue is how much you'll finding yourself using it. You might play it for the frist week or two then forget about it, which is what I think would've happened for me.
If you think you'll get a lot of use out of it then I think you'll enjoy it.
Well that was a fairly long reply, sorry to bore you to death.
