I’ve used Nokia X6 and iPhone 3gs in parallel for about a month now. People considering buying Nokia X6 should compare it against iPhone 3GS first.
- battery lasts up to 3 times longer (and it is easier to find a charger across the globe)
- better coverage (meaning also faster 3.5G internet at countryside places where iPhone switches to slower Edge or GPRS connections)
- better voice quality
- free built-in guided navigation Nokia Maps (but some maps need to be downloaded)
- better camera with flash
- better price
Nokia X6 downsides compared to iPhone 3GS:
- keyboard is uncomfortable to use – takes longer to type
- overall usability is often confusing
- replacing SIM card demands more effort and removing battery
- less good apps (lack of good Twitter app etc)
Overall, although Nokia X6 has many hardware advantages over iPhone, I rather “suffer” of hardware drawbacks, but benefit from better usability and applications of iPhone. I recommend not buying Nokia X6 unless you’ve tried iPhone.