i am going to give you solid, genuine advice that many on this forum are going to hate on, but get the iPhone 3GS and avoid the iPhone 4 at all costs. the iP4 is a PROVEN defective device. stay away. i do HIGHLY recommend the iPhone 3GS though. its fast enough, looks better, feels better, is more reliable, is more durable, and doesnt have useless gimmicks (facetime). i returned my iPhone 4 and will be getting the 3GS.
Apple fanboys, GO!