Like the sucker that I am, I tried Onlive, way way back in the day, and it was very good. I didn't play any competitive games, but single player games were fine, and this was with the internet speeds of the time.
more recently, I've tried Nvidias game streaming and also Gamepass cloud, Playstation streaming, they work well, but you do really benefit with a fast internet connection and know how to set up your network, router etc for the best possible experience.
1Gb fibre here and all the correct ports open, and high speed gubbins and settings and it's really really good. I still wouldn't want to try fighting games or twitchy smups though!
The biggest problem for me, is what you lose, like custom resolutions and mods for games etc, and you never actually own them!