It certainly hasn't been w/o growing pains or detractors.
I still occasionally get rooms or spaces borked, and that frequency increases if E2EE is enabled.
The current server implementation is not svelte in the least, but that's a problem that's being solved with new server implementations that are already 90% of the way there (look-up Dendrite and Conduit if you haven't heard of them).
To be clear, GrapheneOS was running on much older matrix room versions and the bugs that were causing the issues have (to my understanding) largely been mitigated in the later room versions. Of course it's not ideal it happened, but I wouldn't expect the same set of issues to persist after the upgrade, the mitigation has already existed it's just GrapheneOS (understandably) wanted to avoid the disruption of an upgrade if possible.
That makes sense... I was having trouble with E2EE rooms with my friends back when Element was (regrettably) called Riot, but we also chalked that up to being (somewhat) early adopters. That didn't stop us from migrating to Discord, sadly.
It's why I characterised them as growing pains... I'm sure it'll all work out eventually and I've no doubt it's more stable than it has been.