my experience with windows 10 was positive for most of the time, I read some good feedback in a similar thread a month ago and decided to try it out. took literally about an hour for it to update from win8 to win10 without any additional downloads, the system did everything. it's overall fine after you disable some useless apps and enable some good ones, plus they did good in terms of customization and some apps they offer (onenote, flipboard) really come in handy. didn't really give me any significant boost nor any troubles with any game but I noticed that tf2 starts much faster now, dunno if that is because of w10 or it's something else
there's also a nice app for their classic card games, gonna try and find mahjong in their shop later