Having used Windows 10 for over 6 months, I have to say I'm impressed so far.
When running on hardware, it's fast, smooth, has very low memory consumption. Generally gets out of your way. Multiple monitor support is best I've ever seen on any system. A lot of my pet peeves have been fixed, even the age-old Command Prompt is fluidly resizable, supports easy copy & paste and just generally feels... better. Still far cry from OS X Terminal or numerous Linux terminals, but it's getting there. Oh, they put in multiple virtual desktops too.
Remote Desktop works very smoothly and nicely now remotely over 4G mobile phone, 30/60 fps scrolling with all the window drop shadows and Youtube videos running. It looks the same remotely as locally.
However, Windows 10 Pro is still only supporting one simultaneous desktop session for whatever reasons. Consumer versions of Windows should finally start to support multiple remote sessions.
All this from a guy who loves to hate Windows. Typing this on a Macbook running Linux in VMWare Fusion. :)
I run Ubuntu now and yes, there are problems that go with that, but surprisingly hardly any with the OS itself (my arduino refuses to sync with usbtty, one or two odd, but harmless bugs, some really annoying ones Octave cant print most graphs(if they have too much dataon them) to anything different than pdf) - the core is solid, able to work with most cases straight away. Windows?(I work with win 7) You want rar? How about converting .xps to anything useful? Just from the top of my head
Disentangling some stuff(yay, regular start menu updates! Does it even matter?) from the piecemeal core won't fix the most glaring problems, IMO
Support ReactOS and you'll get both the control you have in Ubuntu, and a lot more!
Now Windows is going to be on version 10 for a long time.
They should have just called it Windows X, or winx for short :p