Just did it last night. Games run significantly better, launcher was broken for about 2 seconds, had to re-install windows media player (mostly cause I had Windows 7 Ultimate N). You can essentially turn it into Windows 7 with better performance, so why not? Also, for those who missed out on Windows 8, the cold boot of an SSD is insanely fast.

My DX11 glitch from XIV is ALMOST gone, the player and NPC names would constantly get jumbled, it still happens but far less frequently.