Xbox Cloud gaming has the worst UX out of GeForce Now, Stadia and itself, unless you use it from an Xbox (when it's only utility is that you don't have to download to play). Start-up times are rather long, at least here in France, and games require a controller (even games that would be a million times better to play with a mouse, like Football Manager or Cities:Skylines). There's no way to explore the games available from an Xbox, you have to find a game and select cloud instead of download/play.
It does have the massive advantages of name recognition, lots of games and more importantly, first party exclusives and subsidised prices, so it will probably be the main cloud gaming platform in the future.
It does have the massive advantages of name recognition, lots of games and more importantly, first party exclusives and subsidised prices, so it will probably be the main cloud gaming platform in the future.