impressions, please! i preordered a psp slim silver at gamecrazy; hope they have it in today!
I haven't played one of the old models in a long time so I'm going by memory only.
It's definitely lighter and thinner than the old model. Even after adding the battery it feels like something is missing. This combined with the battery slot cover (it feels like it can break easily), the new UMD slot (it has a lid like a cheap CD player and you just drop the UMD in), and the new surface made it feel kind of like a cheap toy. That went away as soon as I turned it on, though.
The new screen is beautiful. It's higher contrast, has better colors, and the screen handles movement much better. I didn't see any motion blur but I was only playing Jeanne. It's probably brighter but I don't have an old PSP to compare it to (this is much harder to judge for me from memory). The controls are better than the model I had. I remember having a problem with one of the diamond buttons hitting the edge of the screen or sticking and that's gone. The nub feels better than I remember. You'll have to try these out for yourself, though. The new surface protects against smudges really well. After playing I didn't see any thumb prints anywhere which was an annoying problem with the old system. Battery life seemed the same. I think I played ~5 hours before needing to recharge (hmm, might have been closer to 4). I can't compare the load times with the doubled memory, obviously. I'll just trust that they're slightly better. The sound, well, it's pretty bad without headphones. I had a hard time figuring out was being said until I switched to my Senns, then it sounded great.
That's everything I can think of. Overall, I'm impressed by the system (and by Jeanne d'Arc). Sony made good changes where it really counts and if it feels more like a toy than a fragile piece of expensive gear, oh well.