I'm kind of like
@Superfan97 in that I keep an old desktop as the main "repository" of all my media. That's the machine that gets backed up to idrive and is my goto for serious, sit-down work.
I unfortunately "forced" an upgrade for it on day 1 of the Windows 10 release and it had several problems including sound and even the start menu and "metro" apps crashing. I took it to the MS store but they were not able to make any progress with me waiting and were swamped with updates going on in the back room, so I haven't even set it back up yet. Could be that updates have come that will address some of the issues.
Based on that, I would recommend people wait until you get the message that your upgrade is available and not install 10 until you get it.
On my Surface Pro 3 tablet it works just fine. I was a little disappointed that the webcam wouldn't automatically set up for MS Hello (biometric login). I need to research that a little more.
On Windows 10 itself... I'm one of the few people who actually LIKED Windows 8, especially on a touch screen device. When Win8 first released it was terrible on a machine with no touchscreen, but it changed to include the "x" to close a window, etc. Windows 10 has both a desktop and tablet mode, and it switches automatically depending on whether it detects a keyboard or not. Even in tablet mode, however, it doesn't have some of the swipe actions that were so convenient in Win8. On Win8 from the start screen you could just start typing and it would automatically search. On 10 you have to go to the search box or say "hey cortana" if you have that set up.
Another thing that changed (and I think is still evolving) is the way that OneDrive works. Right now in 10 you don't really have a separate "app" for it, it just opens explorer. This is good and bad, since it treats that storage as if it were part fo the machine, another hard drive. I'm still not clear on how it "syncs" the files though. Is is actually copying them all to the hard drive as well? What good is that? The beauty of cloud storage is that it's not taking up space on my HDD. There's a bit of fanboy drama on this point, with the feeling that this will all change as they update backend processes.
The new browser, MS Edge, is very fast and intuitive, and has been clocked in benchmarks faster than both Chrome and FireFox.
I am very excited for the new phones, supposedly being announced in October. Everyone assumes they'll be named Lumia 940 and Lumia 940XL, with both a 5" and 5.7" version. They'll have removable batteries with expandable memory, 20mp cameras, hexa- and octa-core processors respectively, and 3gb(?) of ram. They'll also be able to plug into a USB connector (to a monitor and keyboard) and switch to PC mode. They'll also reportedly work with the Surface Pen.