Game Pass is a great value.
$5 for access to a wealth of PC games - many which aren't cheap, bundled, or whatnot yet...and especially ones you can play early (i.e. M$ games on Day 1) - is awesome.
Game Pass is for games you don't want to spend $60-120 (depending on Edition) early on. It's there, so...you play it and get your $5 worth on it, for that month.
It's also great for games that aren't that moddable. Seriously, without true access to these game-folders, since Microsoft App's from their store require having to try to get "ownership" for those folders & other madness - even though there's now supposedly mod support here in a recent update - eh, it's likely a pain in the neck to try and do any sort of modding here.
If you are going to mod stuff - yeah, you just might be better off w/ other versions. Steam, GOG, G4WL games, games from other places, games that have source ports, etc - usually you have access to these game-folders and you can mess around w/ those w/out hoop-jumping - so, in many cases, those games are just better to own from GOG, Steam, etc etc...basically, do not get those from Game Pass; get it anywhere else.
Game Pass/W10 Store games doesn't really let you copy folders. You don't have access - so, often...best you can do, without having ownership of the folder, is basically use "Apps" from Windows Start menu and only can basically delete it or move it over to another drive. Steam, GOG, G4WL - that's all easier, as you can often move folders, copy files, or whatever of that sort.
Game Pass great for short games. Worried about getting your $5 or so per month? Well, play some of the shorter games on there purposely - as you'll likely finish those within your one month of access that you're paying for.
Also, some games...you might notice b/c they are on Game Pass. Maybe you never would've noticed a game, as it could get drowned on Steam b/c there's so many games there already there - but on Game Pass, it's more visible and promoted better there (on a store w/ curation and advertising certain games better). Maybe you never would've played this game or bought it elsewhere - but heck, it's on this Pass and you're paying for access to it by subbing, so...why not give it a shot ASAP? [shrug]
I don't know if Game Pass is great for big, long-winded games...and dealing w/ their save files. For example, big RPG's - I don't tend to always finish them in one go around. Sometimes, after 20-50 hours, I need to get away from them, as I still ain't completed the main quest. Those games can be big, get repetitive, and whatnot...after some time with them. You just need a break from it. Those aren't always conducive, to play in Game Pass - as who knows, if you can finish some of these by the time your month is up...unless you plan to keep subbing. Those games, you know you're going to keep playing - might be better just to own those elsewhere.
Plus, if there's issues b/t Game Pass versions and say they can be different from say a Steam version or GOG version - you also have to worry about "Will my saved games work from Game Pass to other store?" or you're having trouble trying to pull your save from Game Pass to try to toss into another version like Steam version - yeah, might not be the best idea; who knows if it'll work. [shrug]
Some games have different versions, problems, or content missing that are on Game Pass. For example, some of you guys mentioned Metro Exodus - yeah, that version has issues exclusive to it, on Game Pass. Some times, the Windows Store version is not as up-to-date either. Sometimes, 3rd party games on Windows Store don't have their DLC's (like Wolfenstein II or Metro Exodus). So, in some ways, you just might be better off...with other versions of the game.
ing around got both of them working eventually. (Though the networking error revisited me this week after not bring an issue for a year or two.
Man do I ever regret clicking that. 
