There are some pretty awesome upgrades under the hood that I would really enjoy. Off the top of my head, I don't remember a time where a newer OS can run on older hardware than the previous OS and yet support the latest and greatest technologies. And yet, as you say, they "ruined" it with the metro interface. I don't doubt I I'll be able to get used to it, but playing with it on my laptop, i found metro to be ho hum. I hate that you can't run multiple metro apps simultaneously and viewable at the same time (you are limited to at most, 1 full metro app with a mini-version of a second metro app relegated to 1/3 of the screen on the left or right). The idea of multi-tasking within the metro UI has gone from assuming you can do tons of things at once, limited only by the hardware, to only being able to do one, maybe two things at once. I don't see this as a step forward on something as powerful as a Core i7 and multiple monitors.
Taking a step back and instead of using Metro apps as the be all, end all, The metro screen can simply become a launcher where you go to launch seldom used apps, similar to the existing Start Menu. All other common apps can be stickied to the task bar or desktop. That hasn't gone away. So with the $40 price, this is how I see myself using Win8 and giving it a good chance to see if I can get used to it.
The proof will be, after using Win8 for several months full time, if going back to Win7, I find that I wish I was back on Win8. Time will only tell.