Love it. As a computer engineering student I got early, free access through uni and installed it on both my netbook and desktop.
Firstly it has one of the best multiboot managers I have ever used. My netbook has Win7 on a seperate partition and Ubuntu 12.04 via Wubi and it was able to integrate Ubuntu into the boot menu perfectly.
Startup times are nice and fast, memory utilisation is even smarter than Vista and 7, the new semi-hybernate shutdown is marvellous.
The new task manager is every power-user's dream. The amount of information available right there is spectacular. It is also organised and divided up and highlighted in a way that the info you need is easy and fast to pick out. Having processes and services all grouped together yet organised is great for seeing what sort of resources everything is using is such an improvement.
The power-user menu is great (right click bottom left corner). Every important administrative tool or location is available there. That is something Windows 8 does really well, grouping things together.
Searching is great in that it displays so many results. Often in Win7 if I was looking for something slightly obscure the Start menu search was lacking in number of visible results. Splitting results into apps, settings and files was a good idea too. Got a little fiddly at first but using the cursor keys and hitting enter made it very useful. There are also hotkeys to immediately open search at the desired field: Win+W for settings, Win+Q for apps which also doubles as a shortcut to the all apps list, Win+F for files.
Now the big one... Start screen.
At first I thought it wouldn't work and then I gave it a go in the dev preview and I could see how it could work but it was in need of much improvement back then. It got better and better through the various previews and the final version is actually really useful. When I open my Start menu I can immediately see if I have emails; messages via Skype, Facebook, Windows Live/MSN and Google Talk (All in the wonderful IM+ app); I can see what the weather forecast is and how the prices of my shares are doing.
At first it may look like everything is spread out an therefore takes longer to reach with a mouse. The actual reality is everything is bigger while using the entire screen so more things get put onto the screen while being faster to click as less accuracy is needed. There is some interesting readings about the design here. [http://blogs.msdn.com/b/b8/archive/2011/10/11/reflecting-on-your-comments-on-the-start-screen.aspx]
I personally don't get the people who cry about lack of multitasking because of Start screen. Whenever I use Start menu my focus is completely removed from anything else on the screen. It just makes sense to utilise the entire screen rather than waste space on keeping out of focus content visible.
Lastly here are some keyboard shortcuts that I use all the time:
Win+Q for all apps list and apps search field
Win+W for settings search
Win+F for files search
Win+D for desktop
Win+PrintScreen to save a screenshot to dedicated folder in My Pictures
And a big list of shortcuts that has the new Win8 ones included:
EDIT: I must add that my grandparents wanted a laptop so I directed them to a cheap Asus ultrabook with a touch screen and Windows 8. They love it and find it easier to use than their old desktop with XP. Everything is intuitive and the typography design focus makes things more obvious for them.
EDIT 2: How could I forget! Ribbon in explorer is amazing. Everything useful is right there and easily discovered. Invert Selection? Yes please! I LOVE the Explorer Ribbon.