I have switched over. To me, the basic features are pretty much the same as Windows 8.1. With the exception of them allowing start menu (excellent move) and non full screen apps, not much has changed.
I understand they added the Cortana feature, however, anything I've asked her to do could be done at least 5x faster by me. With Siri, the response is very quick (still not instant but quick). Also, I can ask Siri many things and she will provide instant information where as Cortana will just search Bing for 9/10 things I ask. I hate Bing and they've restricted Cortana to it. This alone was enough for me to disable Cortana all together. I think maybe voice assistance is unnecessary on computers right now because I can move so fast on a computer that something that needs to poll a server off-site for answers is just going to slow me down. Siri makes sense to me because I can't move as quickly on a phone so this makes her much more handy. Perhaps this is why Apple hasn't integrated her to OSX.
As far as the start menu goes, I feel very limited. If I want to have a special list of programs or links to common folders on the left side of my start menu I should be able to. Why is this not an option? I'm stuck with a 'Most Used' list that clearly doesn't know/care what I actually use most. This list is basically useless and taking up space. Even if I turn this off I'm stuck with this dead space over there. This frustrates me.
Now, the Virtual Desktops feature I am a big fan of. This is a great option and I am super happy they added it. The only thing I think they missed out on with this is the option to apply desktops to multiple screens. Say I have desktop 1 on my first screen and I want desktop 2 on my second screen. Why can't I do this? Although I get that it's a niche market for people who use multiple monitors. I will keep my fingers crossed for this though.
The new snapping feature is also a HUGE improvement. Being able to use halfs or quadrants is nice, but the option to pick how you want to use the other portion of the screen after snapping a window into place is a superwin. I love this!
The notifications panel is very slick, but I don't like that I can't choose what I want to show there. Again, the restrictions degrading user experience.
Overall I have mixed feelings about Windows 10, but I like their move towards little innovations which I've always found them to lack.