I changed due to not liking the moto droid keyboard. I used the iPhone for a year before i switched back to verizon and got the moto droid when it came out. So i never used the keyboard. I hated the bulkiness of the droid due to the keyboard. That being said...
I have few customization complaints with the sense ui stuff. But overall im really happy with it. Feels much better in my pocket then the moto droid. Much smoother and you can tell big performance upgrade overall.
Unlimited Text & Data
Former AT&T, Sprint, Nextel Partners, T-Mobile and Cingular (back when separate) customer.