I have upgraded. For $30, I approve.
Launchpad is turning out to be handy for accessing applications that I don't use often enough to warrant placement in my main app bar. Apps that I'd often have to kinda search for in the Applications menu are now organized by priority on my first 2 Launchpad pages. No problem getting to any of them quickly, though I still will likely use Quicksilver/Spotlight the most.
The feature that opens all previously open apps after restart is awesome. This probably isn't so great on a standard HDD, but on an SSD? Every app is open inside of 10 seconds after a restart. Everything right where I left it. Amazing.
Missing Control is fine, though I do not like that it doesn't show minimized (yellow button) apps at all. I don't understand why it wouldn't and hopefully an update will resolve that.
Their take on full screen is really nice and I can see apps like Premiere, Photoshop and others benefitting greatly from the option in the near future.
I've not spend much time with the revised Finder window. Everything else works as it should, save a few features for apps that need updating (like proper DTS audio pass-thru in VLC or MPlayerX over Optical).
It's still OS X. Just with some nice features.
edit: and yes, I too disabled Natural Scrolling. Not because I couldn't have gotten used to it, but because I didn't want to. It would cause too much confusion going from one computer to another. If PCs adopt the reverse scrolling, I may consider it. But until then, I'm happy with scrolling like I've always scrolled.