Well it's not a system seller for me since I already owned Xbox when I joined game pass. But it's an amazing service. I don't personally understand the need to own all the games. Especially physical copies are just a nuisance.
I can see it being an incentive to buy Xbox though. You get plenty of games to play for decent price and those console exclusive games are excellent. Most of them at least. Microsoft just needs to market this service Even More, there's too many gamers who don't know what it is.