That is a pretty nice load of games there. If you can continue to claim all the previous months games, I'd say it's more like Gamepass than PS+ or XBL. I didn't realize that there was that much included stuff. The main complaint has been that you have to sub, then you have to pay full price for everything that you want to play. But, since there are a bunch of games included with the subscription, many of which are AAA quality, that complaint loses *some* of its substance.
None of those are current games, with the exception of Destiny 2. So, you can't play whatever you want. But, there is good content there.
Some day, I'm going to try Stadia out....
You can claim games from the last three months or so, although it doesn't seem to be a strict rule. Destiny 2 was in from the beginning, on the other hand I don't believe Kona was already available for three months, this one seems to have been gone faster. Anyways, most games stay available for a while, and once claimed you can play them as long as you are subscribed.
I personally think the subscription is worth it with these monthly games, but that is everyones decision. But I would add, that you don't need to subscribe at all. Stadia Base is free, but you have to purchase the games you wanna play (or play free to play games). Stadia Pro adds these games mentioned above as claimable. Also you get some additional sales with Stadia Pro, things you purchased this way stay available after you end the subscription.
I mostly stay with the games I got via subscription (Gylt for instance is pretty nice), but have bought two games not available on Switch as I felt the itch to play them. Assassins Creed Odyssey, as I am a sucker for ancient greece (and the game has nice views and information about ancient greece) and Borderlands 3 (I liked 2, but somehow I am a bit disappointed with 3, maybe Borderlands humour is only working once - or more likely Handsome Jack was just awesome).