SilverWook said:
Free, from a certain point of view. ;)
http://www.pcgamer.com/windows-10-solitaire-requires-a-subscription-to-remove-ads/
It's a small issue for sure but it's that kind of thing that worries. Swapping an awesome OS that I paid good money for like Win7Pro, for a free OS that has features limited, or there's less of them.