The good news is it is a mix of Win 8 and Win 10. You're not forced to have the tiles all the time and you get back the old Start button from Win 7. In fact, while searching for a photo to use for this post, I see that there are many configurations you can have for your Start button. I just have to figure out how to do it.
It doesn't seem any slower or faster for me. I know it will slow down as I add more stuff.
I don't think I like the idea of a Windows app store yet. Not sure what the purpose is other than having a clearinghouse for Windows software developers as well as having a way of verifying software added to the operating system.
I am having trouble with getting the taskbar to hide. So, now, I have to keep it on all of the time and lose a few pixels of space at the bottom. Most people I know have it this way. I don't like it.
Otherwise, it's business as usual in the world of Windows.