So far, I've had no issues with netcode when playing people within the same region (EC Canada and US), but outside of that, it'll start being either unstable or just won't connect at all.
But it's still better than ULiL because after the lobby update in ULiL, netplay for a lot people just straight up didn't work in the end even if you were just doing direct connections, but at least now that works in AoCF.
I know a lot of the single player features are a mess atm, but in terms of core gameplay, the game is really fun and I will agree it's probably the best one. It got rid of the floaty gameplay in HM and refined it in ULiL, and then AoCF got rid of all the terribly gimmick mechanics it had (RNG "weather", occult orb chasing) with something a lot more solid and more fun, especially at a competitive level.
Kinda sucks that solo character combo potential has been slightly nerfed in this game (despite the damage output increase), but I can understand it's to balance the fact that we have access to tag combos now.