Form over function won this time.
While it is definitely a portable I would actually consider taking with me somewhere (easily slips into a back pocket, no extra media to fuss with), the price was what made me laugh and say "guess I'll be sticking with the PSP3000 until the price drops!"
I foresee peripheral makers producing an external battery pack for the Go.
Really do like the form factor though; looks like you're playing with a phone rather than a children's toy.