I love it, personally. Doom has been announced to be coming to Game Pass tomorrow. All new releases from Xbox Studios will be on game pass on release day, so that's great if you like Forza, Halo, Gears of War, and whatever else they come out with. I'll just take a look at the current game pass games and note anything I've played that I feel might be worth commenting on. I enjoy platformers a lot and have never really gotten into open world adventure type games. So, the games I comment on might not be the same games you like. Just throwing that out there.
If you don't already own Rocket League, that's worth playing for a bit of fun when you can't decide on what to play. I still need to try The Division again. I remember playing the Beta, then one weekend when they had a free weekend, but I never came back to it. I've heard it's a lot better now than what it was at launch.
Halo 5 is great for its multiplayer. Honestly, it's probably in my top 2 multiplayer shooter games this generation. Titanfall 2 would be my other one in the top 2. Halo 5's campaign is decent, but a lot of Halo fans hate it. I would say it's the worst campaign out of all the Halo games, but I still played through it a couple of times.
I enjoy the Dirt games, so if I hadn't already 100% that one before it came to Game Pass, I would be all over that. It's definitely more difficult than previous Dirt games (except for Dirt Rally, that game is really hard).
Human Fall Flat looks like it could be a fun game to play with friends and just goof around with.
If you're into Sim City type games, I've heard Cities: Skylines is good. I tried it for a couple hours but just couldn't get into it that much even though I used to play Sim City 2000 when I was younger.
Rise of the Tomb Raider is great, definitely recommend checking that out.
I've heard Ruiner is good. That's on my list to play.
Rush: A Disney Pixar Adventure is a good game for kids, same for Disneyland Adventures. And honestly, I've been playing the former more than my girlfriend's daughter has recently and I've been enjoying it.
ABZU is a beautiful game. It only takes a couple hours to complete, but it's pretty relaxing and worth a playthrough just to see some really beautiful environments.
BattleBlock Theater is a lot of fun, especially if you have someone to play couch co-op with.
Super Lucky's Tale is worth checking out if you like 3D platformers. The camera can be annoying, and the controls aren't great at times. But honestly, I enjoyed the game and completed it 100%. I was able to enjoy it even with those shortcomings.
10 Second Ninja X is basically a speed-running platformer. You have to complete each level within 10 seconds or less, hence the title. I need to go back and play that again. I played through maybe half of it but then started playing other stuff.
Guacamelee is a lot of fun, great metroidvania platformer. I really enjoyed that one when I played it a couple years ago.
OlliOlli is worth playing if you're into skating games, or games where you try to string together different button combinations for combos. It's basically just a 2d sidescrolling game where you try to string together tricks.
Super Mega Baseball is the best baseball game on Xbox, except for its sequel. Definitely worth checking out if you need a baseball fix. Yeah, it's cartoony, but the controls and everything are great.
Late Shift is basically a choose your own adventure movie. I played it and thought it was ok. It was worth watching an ok story while getting some easy achievements.
I've heard The Golf Club is good, but I've never played it.
Max: The Curse of Brotherhood is a really goodplatformer with some cool physics stuff thrown it.
Oxenfree is a nice mystery adventure game. I played through it when it was a GWG and enjoyed it.
IDARB is a fun game, but really only if you have someone to play couch co-op with. Even better if you have a group of 4 or more.
I've heard great things about Braid, but I haven't played it yet. It's in my list of games to play.
Hue is a puzzle platformer that I really enjoyed. Basically you switch between colors to help you complete puzzles or avoid obstacles.
ScreamRide is a game where you build, ride, and demolish roller coaster tracks. I actually really enjoyed it and is another game I completed 100%.
Sunset Overdrive is worth playing if you haven't. I honestly played it when it first came to GWG and I didn't enjoy it very much. I eventually kept reading people saying how great it was so I gave it another shot. I think the problem for me was the movement felt slow and it felt like I kept doing the same thing over and over. Eventually, though, you unlock the better traversal skills and that really opens the game up. The grinding on rails and dashing in mid-air definitely made it a lot more fun. I still only played it for a few hours total after that, but maybe I need to go back to it sometime.
The old Star Wars games are ones that I want to go back and play sometime. I never played KOTOR growing up, and I only played a little bit of the original Force Unleashed. But if you're a big Star Wars fan, those might be worth playing.