Game Pass is great if you want to try a lot of different games and see what you like without having to do research or worry about whether or not a particular game is worth your $$. Especially if you like playing small indie games and tend not to replay them anyway - this way, $10-15 and you can play multiple new and old indie games for the price of one (or less), plus try a few of the big games, and maybe get surprised by games you didn’t think you’d like but gave a shot because they were included. And if you do want to replay any eventually, by then, the price will have dropped and you’ve still saved $$.
This is offset however by the fact it’s still buggy and frustrating as all hell sometimes. I hate the way it works with virtual drives. And it doesn’t work for stuff you want to mod or play the dlc for (no way no how am I actually buying a game/dlc on that platform).