Have you even tried the N-Gage or the PS1 with the flip-top monitor? It's hard to put my finger on it, but it just "feels" wrong. You lose so much of the immersive quality and your ability to pay attention to detail is severely diminished.
It isn't just the smaller screen too, but the resolution is going to be reduced, too.
Plus the price seems like it's going to be far out of the same ballpark as even the Dual Screen, because of all the extra features planned. Nokia learned the hard way that people aren't going to be forking out 200-300+ bucks for a handheld.
Yeah, that was far from the only reason, but I simply don't see it as realistic for a company to offer a handheld that costs as much as one of the major consoles.
I've tried the flip top on PS1 and yes the screen is crap. But hopefully the PSP will have a higher quality screen.
Don't think I'm going to purchase it though.