I'm very disappointed! I downloaded 10 and installed it on my laptop as I'm about to take a trip on the Queen Mary II and didn't want to use up the very expensive, very slow internet by having the laptop try to d/l it enroute. Installation was quite easy, though it took a long time. Now, though, I have issues with the OS.
First - WAY slow! Boot time under 8.1 was 2 minute 38 seconds. Under 10 - 7 minutes 18 seconds! Woah! And what is with the flashing icons on the desktop? Very weird. Very slow response opening programs, too. I mean VERY slow!
Then there was the notification that the Avast firewall was turned off, and finding that I couldn't turn it on. I had to update Avast, then use uninstall to "repair" Avast, and boot twice to get it work properly.
And what about Mail? I have it set to my Gmail account, but for two hours it just sat there saying "Working on it..." or some such. Useless, at least so far.
This feels like a beta rather than an actual RTM version! I'll keep working with it, though, hoping things improve.