It's been amazing value for me - I'd spent a decade away from video games outside of Nintendo, so I had a giant backlog - I've played over 100 in the last 12 months on my Series X.
However, I'm noticing diminishing returns, since I'm spending a lot of time on games like Mass Effect, which are cheap to buy. There's also a lot of games in genres I don't like e.g JRPG, fighting, sports, and also plainly bad games.
The balance of good new games vs ones leaving the service is pretty poor, too. If I wasn't locked into another year, I'd drop it for a while.
TLDR - look at the catalogue, work out how much it would cost to buy the games you'd play, and then decide.