I am proud owner of iPhone 4 for the past 2 and half years. I am absolutely happy with the devices performance. It will meet your almost 98% requirements with regard to phone, browser, GPS, interest specific app etc etc.
Excellent design, till date I never come across a technical issue except one time, but got cleared in few minutes time. Since it is positioned as a premium product it is higher priced compared to the competitors.
Negatives: With the introduction of latest up-gradation of iOS, which is available free for all iPhone 4 and above users, my phone has gone slow, even though latest OS has lot of added advantages, the machine slowness has reduced my delight.