1. Open-source OS (Android), which means I can mess with it to explore new stuff, really cool for developers
2. GPS and GMap Street view
3. 3G data plan at moderate price $25, which is $5 more than my current EDGE plan, but it comes with 400 free sms.
4. full function browser

Missing features that I use daily on my current Windows Mobile phone:

1. NO support to Microsoft Exchange, which means I can't access corporate emails and calendars.(ack!)
2. IM only supports Gtalk for now, but I guess support for other IM's will come out soon.
3. not enough applications available, not to mention freebies.
4. still no turn-by-turn navigation (don't know why)

My choice: I am likely to pick up one, but not sure if that ends up being my primary phone.