The early reviews of the iPhone on Verizon are that it's much better if you use the iPhone as a phone.    Data may be something else.    Solution: Wait for the iPhone 5 unless you truly want this thing or use it all of the time and hate AT&T.

Sample - Laptop Mag's Mark Spoonauer:
The iPhone 4 on Verizon Wireless delivers the reliable data and voice coverage AT&T has failed to provide, making this device a dependable partner for work and play. Everything we love about Apple's smart phone is enhanced because you don't have to wait to get stuff done or wonder if your call will drop.