I think I will upgrade. Here's what I'm thinking:
Cons:
• $30/month data plan instead of current $20/month
• No free SMS messages, so add $5 more per mo for that
• I already have a perfectly good iPhone that still works
• I only use EDGE 10% of the time now. 3G replaces EDGE.
• I don't know how good 3G coverage will be in my area.
• 3G drains battery life at twice the speed
• What if a 32gb iPhone 2 is released in September?
Pros:
• 3G speeds may mean I use my iPhone more when away from wi-fi
• 3G speeds mean when there's no wi-fi, the experience is better
• GPS will make burgeoning location based services better
• Better reception
• You sound better to the people you are calling
• Much better audio from the speakers (according to Steve)
• Looks a little better with the new design
• The expensive data plan is about like other 3G plans
• I get the subsidized price after only 1 year on my previous plan
• 3G lets you receive calls while surfing the Net!
• Get to see what it's like to have the best 3G phone on the planet
Update: Good stuff you should read - hands on reviews out July 9:
Walt Mossberg, Wall Street Journal
Edward Baig, USA Today
David Pogue, New York Times