Win10 still not quite there yet
A few things are needed to make it excellent. I played with the latest build last night.
1) A fully customizable start menu. If you like Windows 2000 style start, you should be able to get it. Windows XP style, you got it. Windows 7 style, no problem. Windows 10 style, your choice.
1a) The Windows 10 start menu currently shows all programs (look it, on a computer it isn't an app) alphabetically. The start menu needs to go back to a hierarchy layer like all previous start menus.
2) 100% Aero available. If you don't like it, don't use it. But make it available.
3) Return my privacy! Right now, I have to uncheck so many options in Windows 10 (and Windows 8.1) to stop my OS from tracking me. Even after I uncheck all these options, the search box that you use to search programs and files on your computer also searches the web. And guess which search engine is used? It is not DuckDuckGo. And it is actually quite annoying because it seems like web results appear faster than results on your computer. I realize I cannot escape tracking, but that does not mean I should just give up.
4) Return F8! Seriously, removing the option to press F8 was perhaps the stupidest decision Microsoft made in Windows 8. And that is saying a lot. In Windows 8 if your computer gets stuck in infinite reboot loop there is no way to get to safe mode or a repair console to try and fix it. F8 needs to return immediately.
5) Stop hiding system restore.
6) Provide a proper backup program. One like you find with Windows 7, except that it prunes old backups when the disk space is full.