I have yet to take the leap in terms of using it day-to-day. I just don't have the time to play.
I had my kid install it in a small netbook we were not using just to see what it felt like. Neither one of us is interested in using it very far past boot. It's one of those "Right. Brilliant!" moments and then the notebook is closed shut and turned off.
Professionally my concern has to do with wasting time and not being able what we absolutely-positively need to do on a daily basis. As I type this I have about twenty programs up and running on this machine. It has three large monitors attached. It was specifically built to make programming, electronics design or mechanical design far more productive. If doing a web project it is not uncommon to have multiple browsers, virtual machines and IDE's going as well as PDF's and reference material. Similar scenarios exist when doing electro-mechanical design.
My current first-touch experience with W8 is just that: a first impression. And this impression has not been positive at all. I, frankly, don't have time to deal with bullshit. Metro (or whatever they care to call it) might be great for a tablet or for grandma on a single screen laptop. It absolutely suck ass for us. I wouldn't even want it present on any of my machines. What I need is an evolutionary improvement over where we are as opposed to a pole-shifting paradigm shift. I would suspect that if I decided to switch my development machines to W8 (not likely) the process might easily bring productivity down to zero or less for at least a month. This on the assumption that all applications play ball.
What's disappointing here is that, to me at least, it sure feels like MS has more than lost its way. They seem to simply not understand who uses their machines and what they need to do with them.
I get it. I get it. Grandma, uncle Fester or cousin Itt might need a dumbed-down single-finger point-and-something-happens interface so they can waste five hours a day on Facebook. However, the massive population of users who needs these machines for business, engineering, design, industrial and other applications don't need this at all. They need the ball to keep rolling in the same direction. Less bugs. More speed. Cheaper. That's it.
I was hoping that the day might come when MS might fully embrace Unix/Linux as the core underneath Windows and move us all into what could be a really neat platform in a manageable way. Of course, it is lunacy to even think that this could be possible. Then again, I present you with Windows 8.