I'm running the iOS6 GM on my iPhone 4 and it's a major disappointment. It's missing a LOT of features that could run on the hardware but Apple decided to leave out to force people to upgrade.
Well, they got their wish. I'm going to upgrade... but not to iPhone 5. I've had it with their bullshit tactics. I'm getting either the Nokia Lumnia 920 or the Samsung ATIV S, both running Windows Phone 8. And hopefully droping AT&T for Tmobile. Can't wait till Xmas!