I am also using an unlocked iPhone on tmobile. It does everything I wanted it for and more. It will be interesting to see how the new ones will be obtained to use on other networks but if Tmobile has 3G in my area I will do my best to get one. I have considered switching to AT&T but have not found enough of a reason to make the change yet.

I got mine for 400 dollars and believe I have gotten my return on investment for as much as I use it.