Almost everyone I've read over the past couple of week, those that hate the new UI, seem to me to not be very adaptable. They would rather tear something down than spend about 5 minutes to master the new UI. They fight it the whole time because it isn't Windows XP. However, I agree the radical difference between desktop and Metro is jarring at first, but in just a few minutes I grew to love it because finding things, starting things up, and the SPEED is much more productive.
I agree 5 minutes of training for the standard Drones out there is probably too little, you might need 15 minutes, but that would be LONG for those who already use Windows 7. For those of you who are reading this post are rather technical people, who understand computers and should give it a chance.
Learn a few keyboard shortcuts (there are many), and spend a few moments thinking about how you work, and I believe you may change your minds.
Now, could MS have done differently, like make the Start button an option. Yeah. And maybe they will, but you DO NOT NEED IT!