I did the Assassin's Creed: Odyssey playtest at the end of last year. My first couple weeks with it were shockingly good, considering the sometimes-carppy Verizon wifi and ancient PC setup I was using. When the connection was good, I was getting a console-like experience. When the connection struggled, the visual quality would dip and I'd get hitches, but for what it was I was pretty ok with it.
A couple weeks in it suddenly took a nosedive, frequently booting me out to the login screen during play. I could always get right back to my session with the game paused right where I left off, but it put a big wound in an otherwise very enjoyable experience. Never was able to determine if it was because my Verizon modem/router decided to stop playing nice with their cloud or what, and the playtest didn't have the sort of robust knowledge base and support options that I would expect a launched product to have.
Based on all that, I'm cautiously optimistic. The good was very good, and even the problems that came up later demonstrated a little of their ability to instantly hold and jump back into a saved state. Their dedicated cloud hardware looks pretty impressive, and gives me more assurance that they're taking this seriously and not just trying a "look what we can do" show. I'd like to see them talking about pushing providers to up their bitrate and stability game too.