I definitly see why it can be an interesting offering for some people, but it's clearly not for me.
I would hate to be "forced" to play a game because it's leaving the service. I buy a lot of games yes, but playing at my own pace is essential and such services just push you to follow the flow of new and departing games.

I've been trying a few games in XGP but it lacks a basic feature for me, playtime tracking. For most of the games I tried, it didn't work.

So how long do you play one game? One hour, then you abandon it and move to another game?

As I said in my reply, I guess a game subscription service works for people like you who use relatively little time per game, and are not like me who might spend weeks or even months on a big roleplaying game, or play one online shooter for years and thousands of hours (= Team Fortress 2 for me), instead of serial-hopping to other online games.

By the way, how old are you? It is usually only later in game when you become nostalgic of e.g. games or movies or music you experienced earlier in your life, and start to understand why anyone would want to maybe "own" and relive such experiences, or maybe even show them to others. Back when I was at my teens, I was also "need to play as many new games as possible" frenzy. Things change, now I am not in a hurry to play as many games as possible per week. Luckily for me, I've been able to relive many of those childhood experiences through e.g. emulation.

Games are not like movies or TV series or Youtube cat videos for me. I can fully experience a full movie in !½.-2 hours and never come back to it, but that is hardly ever possible with a game.

That is not quite clear to me about Game Pass. Do games disappear from your account as with streaming gaming services, or do you get games to your account for a fixed monthly fee, like the Humble Bundle monthly system or whatever it was?

Yeah I'd hate it if some big RPG game disappeared from the service when I haven't yet finished it. With movies in Netflix etc. it is less of a problem as finishing a movie doesn't take more than 2 hours so it is quite unlikely a movie would disappear just as I am watching it, but I have recently seen some column of a journalist bitching about how some TV series disappeared from Netflix or such when he was still watching it with his wife, and gave them familiar "this would have never had happened in the old times if I had had that TV series on a DVD or recorded onto VHS tapes from TV...".

Yeah, some people become enlightened about all this DRM and "media ownership" stuff only after it has bitten them... :D

(Well, frankly, so did I. I became anti-DRM back when the Steam client suddenly stopped supporting Windows 2000, and suddenly I was unable to play my Steam games on my Windows 2000 PC, just because Valve had decided so. That was the wake up call for me, when it comes to "ownership" of games and media. Do I really want someone else to have the total control of when and where I use my media and games?)

Humble bundle's subscription service does just that. They have the DRM-free treasure trove and a collection of drm-free and/or steam games.

Fair enough questions I suppose. I finish the vast majority of games I play, but I do play one at a time and play them until I finish them. Last year I played and finished...I think it was around 80 games, maybe half of them on Game Pass. You can go through last years Games Finished thread if you want. Not just short games either, I played a lot of games that are 60 plus hours long.

I'm 50 years old, I used to play Space Invaders on the way home from school on an old coffee table machine. I know what nostalgia is. I have a large boxed collection, one of the largest collection of board wargames. I know what owning is. And today I know good value is. And if the game I play on Game Pass now I get nostalgic about in 10 years time...they are digital, I'll get them and find a way to make them work somehow. They will still be obtainable...and probably really cheap. I'll worry about then. But there's really only a handful of titles I've ever played multiple times anyway, I'd rather new experiences. Game Pass suits me perfectly. Especially because I haven't really even paid for it for over year, and looks like I won;t have to now until about July next year.

To answer some of the questions you had lower down. If a game leaves the service, it still stays installed you still have your saves, as long as you don't deliberately delete them or format your drive and cloud saves. If you then buy the game later from the Win store or on Xbox console (if it's a play anywhere cross platform game) you take up where you left off. Sometimes games even come back to the service. It's not like streaming, they are regular installed games exactly as the ones you buy from the Win store.

It's not their main draw though. If Humble Monthly would just be the Treasure Trove, it could never compete with Game Pass. The games in the Trove are usually small or old, and you can easily exploit or bypass the subscription system by just buying Humble Monthly once a year or so (for the more attractive monthly games) and then download all of the accumulated DRM-free Treasure Trove at once before unsubscribing again. If GOG did something similar without the Steam keys, it would either be not very attractive to most because it would contain games that most avid gamers already own, or it would be so much better (and more exploitable) than what Microsoft offers and most probably diminish GOG's revenue if the games were as new and expensive as those offered in Game Pass.

I really don't see it as a replacement rather than as an additional source of gaming, particularly those games that are DRMed one way or another. If I'm getting games that amount to little more than rentals anyway I might as well pay accordingly. ;) It's also a good way to try some games I'd be otherwise unsure about but don't have actual demos (or stupid time-limited ones).

Not that I'm lacking games to play without it, but that's beside the point. I also don't see myself continually subscribing. I'll just do a month here and there when there are games available that may be of interest, i.e. when Dragon Quest 11 Definitive hits. ;)