Blackfriars's communications has an interesting discourse on why the practical difference between 3G and EDGE cellphone data networks is less than it appears to be based on a naive bandwidth metric. Their argument is that the user experience of TCP/HTML is much more impacted by latency, error rates, and processor speed than by bandwidth — and Edge had the edge on all three. Additionally, EDGE may consume considerably less power."
Ars Technica did an informal analysis last month and determined that the Samsung Blackjack lasted 22% longer using JUST EDGE vs using JUST 3G. 3G (as it stands now) is a drain on the battery. In my experiences, 3G isn't that much faster anyway. In my area, there is no 3G implemented (yet) for AT&T - so it's moot for me any way. Would I like the speed of the EDGE network to be faster? Yes! Is it acceptable for me for what I do? Yes! There's rarely a time when I'm not near a WiFi hotspot any way.