I bought an 'unlocked' iPhone at full price with the expectation that I would be able to use it with the carrier of my choice only to discover that I can't.
I was without any mobile data for nearly a month because the unlockit.co.nz "solution" for modifying APN settings wasn't working for me. I tried it again (randomly) a week ago and data came back. Still no MMS.
I guess I should have bought an Android device, but I was so disappointed by my previous phone (Droid 2) that I'm hesitant to purchase another non-Nexus device. I also develop iOS apps and need something to test them on.