Apart from the occasional hiccup, quality is fine. I am sure that if you did a side by side comparison it would be obvious, but I can honestly say I don't notice 99% of the time. Once you are in a game and playing, it is totally fine.

In the same way that when you are watching something on netflix or amazon or disney etc, when you are really into the movie or show no one ever stops watching and thinks "gee I just cannot watch this - it is not Blu-ray quality!".

Just like with netflix et al, game streaming is amazing - pull out a thin and light laptop, browse through a large catalog of games and just pick something and play immediately. The "legacy" approach is wait until you can physically go to your gaming PC or laptop (because you need the hardware), wait for it to boot, wait for the inevitable updates to download for Windows and Steam and Graphics drivers, browse through your game catalog, wait to download the 20-30gb install, wait for the VC redistributable to install, then wait for the game itself installs etc. It sucks - you waste so much time. With a Chromebook and geforce now (rest in peace stadia) I can literally go from a closed-laptop to in-game in about one minute, and I can do that anywhere too. This is the future. I have loads of games on steam that I have never even played - if I could just play them immediately with a single click you can bet I would have at least given them a go.

I personally have very limited spare time, so I would (and do/did for geforce now and stadia) pay extra for the convenience of stream so when I get a spare 30 mins I can play a game in that time, not spend it only getting halfway through a game download in steam. Just like I pay for the convenience of netflix et al rather than buying dvds/Blu-rays and having to watch everything on my TV.