iOS Flaw: WiFi vs. 3G
Sorry, tough to explain my issue in a brief title, but one of the more annoying things about the iPhone (and likely other smartphones) is the issue where you walk into a public building that offers WiFi, but that WiFi requires some sort of authentication, usually a screen on Safari where you just click "OK". Caribou Coffee is like this, so are a few other retailers like Home Depot, Target, etc. (I'm not saying this is the case in ALL of those stores, this is just where I've experienced it).
Why is this a big issue? Because it effectively shuts down your data connection but "preferring" a WiFi connection that actually doesn't work. Unless you are prompted to go sign in or click "OK", any text you send, or any data you try to work will no load because you are not "allowed" to use the WiFi. Ironically, were there no WiFi there at all, your 3G connection would probably work just fine in most buildings.
People will say this is an easy fix, or that I should just turn my WiFi off, but I use WiFi all the time at home and at work - that just isn't feasible. The OS should do a better job telling you there's some action required, or it shouldn't defer to the WiFi connection unless that action has been taken.