Honestly, it's not as big a change as everyone makes it out to be, I find that most people that say that haven't really tried it yet (no offense to you @geek, you may have I'm just speaking generally. There's a lot of W8 bashers on the web today). If you take the desktop in isolation it's actually pretty nice, everything moves faster, it's nice and clean and there are lots of little improvements in so many different low and high level places its tough to keep track of them all.
Now here comes the elephant in the room, metro. As far as I'm concerned that whole part has one extremely serious flaw (yes just one). It's really simple, when I type to search any settings and control panel links are hidden behind a category link that I have to click. Because of that one thing I am going to have to go to an alternative like Start8 or maybe just using launchy. That is absolutely hugely annoying and I can't deal with that. I am more than willing to turn off all of metro to make that not happen anymore.
Without that metro isn't bad. It's a bit weird on a desktop yes but live updating tiles and the sidebar view are cool enough that I'd probably play around with it on a second monitor to see what I can get out of it. But that search flaw is a killer, I'm not messing around with a toy if that toy kills my core flow.
But without metro its really just a better desktop. Not $120 better but if you pulled it at a discount I'd say it's totally worth it.
Aside: I'm only talking about tech-savvy users here since this is HTG and that's what I am. Windows newbies are a whole different issue, I really think MS is kinda throwing them under the bus with W8. But fortunately I don't work for MS so that's their problem not mine