One of the biggest shortcomings of the iPhone’s first-generation model was its reliance on AT&T’s slow EDGE data network. The new 3G data support means that the iPhone can download data 2-3 times faster than the old model. Of course, it still has WiFi support, and based on early reviews, you may want to use WiFi whenever it’s possible, because 3G usage will drain the iPhone’s batteries quickly. It’s probably not a must-have feature for most users, but the addition of a GPS receiver is a welcome enhancement. The iPhone OS can now use a combination of GPS data and triangulation from WiFi hotspots and cell-tower locations to establish its location.

This feature has worked well in our testing so far, and we expect its usefulness to expand as an increasing number of applications start to take advantage of it. Thanks in part to heavy demand and insufficient capacity, the phone’s launch today did not go smoothly. preventing many customers from being able to begin using their phones (greatly irritating some users, and provoking mirth among others). We tried for several hours to activate our iPhone, only succeeding about 2 p.m. Pacific — five hours after we’d purchased the phone. The problems seem to have cleared up now, however, and reports suggest that activation is proceeding much more quickly. Part of the activation process must be completed in an Apple or AT&T store, part of it can be done via iTunes.