Several hands-on iPhone 3G reports from after the WWDC 2008 Keynote are out, and as you might expect they're all saying pretty much the same thing. Despite the few extra millimeters thickness over the old iPhone, Apple's newly slimmed edges disguise it well and the plastic - which is a concession to the numerous wireless radios packed inside - feels reasonable, though some question how scratch-resistant it will prove. Apple are claiming it'll disguise wear better than the original. The buttons have been switched to metal for aesthetic, not practical reasons, and are sharper-edged. A few people have suggested that the new, white 16GB handset is particularly feminine, though that's more personal choice than anything else.
Update: SlashGear iPhone 3G review on July 11, 2008