@thebird
It is free, yeah, and other than a few minor glitches it's been fine. I know peopel tend to disregard the error numbers that come up in windows when things go wrong, because for a long time most of them always seemed to come up with answers too generic to be helpful, but I def suggest having a second way to access the internet and looking them up if something happens, before you get too frustrated. For instance, as I think I mentioned, I forgot to disable antivirus when doing an in-place upgrade and when it failed, the error message came back to that exactly. Which... I guess I wish they'd just say that in the error message, but meh.
For those with less than legal versions, or who have WinXP but and want to upgrade but can't afford it: Basically all of our machines are pirated, even the ones we originally bought Windows for, and so far it's worked fine in both the SLIC insertion method for win7 (i.e. duplicating what a prefab company does to mass install windows with a generic key matching a bios table) which isn't really distinguishable from a legit copy anyway, as well as AutoKMS license activation where a scheduled task checks a remote server for authentication every so often, resetting the license each time (except in this place the remote computer is just redirected to your own and always provides authorization). As long as you're not on an Enterprise copy and it can verify that you're authentic in the moment, it'll switch you over to a 100% legit Win10 license.
So far the only big stumbling block I've hit in terms of games, @Thenomain, is that Zuma's Revenge (old ass game, so...) won't load fullscreen without being supersized off the edges of the screen. I think I ran into this on win8.1 when I first got it, but can't remember what I did to fix it.
So far all my list of (mostly steam) games confirmed working is:
Assassin's Creed (3 and 4)
Bastion
Bioshock Infinite
Black Mesa
Borderlands
Borderlands 2
Borderlands: The Pre-Sequal
Defiance
Deus Ex: Human Revolution - Director's Cut
Diablo 3
Dishonored
Divinity: Original Sin
DLC Quest
Dragon Age (All)
Far Cry 3
Final Fantasy (7, 8, 13, 13-2)
Firefall
Half-Life 2
Hitman: Absolution
The Incredible Adventures of Van Helsing (1 and 2)
Just Cause 2
Kingdom of Amalur: Reckoning
The Last Remnant
The Legend of Heroes: Trails in the Sky
Magic: The Gathering - Duels of the Planeswalkers (Original, 2012, 2015)
Mass Effect (All)
Middle-Earth: Shadow of Mordor
Neverwinter
Orcs Must Die (1 and 2)
Path of Exile
Planetary Annihilation
Poker Night at the Inventory (1 and 2)
Portal (1 and 2)
Saints Row (3 and 4)
Shadowrun Returns
Shadowrun Dragonfall - Director's Cut
Sid Meier's Civilization: Beyond Earth
Sniper: Ghost Warrior (1 and 2)
Spec Ops: The Line
The Stanley Parable
Starbound
StarForge
Strike Suit Zero - Director's Cut
Team Fortress 2
Thief
Tomb Raider (2013
Tom Clancy's Splinter Cell: Blacklist
Warhammer 40,000 Space Marine
Warhammer 40,000 Soulstorm
That was some exhausting shit to check out. My Bejeweled is having the same issue as the Zuma's Revenge, so I think it might be something with my video drivers and old ass Popcap games never meant to run on a 1920x1200 monitor in the first place, rather than something about Win10 in particular.