My experience with Stadia has been pretty great. Since November 2020 I've been playing Destiny 2, an MMO FPS, so perhaps the worst-case latency-requiring kind of game, and it's been pretty great, at least for PvE activities. (PvP has been less great, but perhaps that's more the fault of my aging reflexes than near-imperceptible network latency)
When traveling, I've been playing Destiny on Stadia on an iPad (!) with an Xbox controller paired, using the host Wifi.
That, alone, was enough to sell me on the value of Stadia. I'm gladly paying the $10/mo (half that of GeForce Now) for the Pro tier, which gives me 4k HDR, and a bunch of games free each month.
People like to harp on Stadia, and it's true that their player numbers are low. In fact, a couple of days ago Destiny announced availability on the Epic Games Store, and apparently on Day 1 the number of players via the Epic Games Store outnumbered the number of Stadia players by 10x. There was a promotion on Epic which helped, but still, 10x!
Google has certainly tarnished their brand by killing well-loved products, but I also feel like they're under-promoting what they have. For example, if I try to go to stadia.com right now from this mac/safari, I'll just get a page that says "Stadia requires Chrome", with no promotional content to entice the user.