As it stands now, it is nearly unplayable in multiplayer.
The problems me and my friend(s) face are staggering.
We had set aside an entire weekend each, to meet online and finish BG2 from Chateau Irenicus to ToB.
Alas.. Saturday afternoon we decided to fold and give up, possibly do it in a vanilla BG2 installation using Hamachi to connect at a later time.
What we experienced:
Numerous incidents of NPC's spawning in the wrong place, often breaking quest chains:
Yakman from Watcher's Keep spawned in Firekrag's lair, went hostile and of course was killed.
The Genie in Chateau Irenicus spawning 10 feet away from the Duergars.
.. the list goes on, and it seemed entirely random.
The Chromatic demon spawning outside of his cage, and in the fight staying as an Ice element the entire fight allowing us to just kite him around and kill him with just Firetooth..
Not ONE of us could reproduce these kinds of insane bugs in singleplayer.
Savegames becomming unplayable on Guest clients.
The host would never have this problem, but the Guest clients would at times be entirely unplayable.
The game would hitch for 1 second, every 2 seconds.
Reconnecting, rebooting, nothing helped.
Rolling back to a previous save (and losing progress and time..) was the only alternative.
How do you even break a specific savegame like that??
Losing sync, losing connection, Host client would crash quite often (we swapped around roles several times for testing).
Beamdog.. the game has been out for a long time now, you have been very nearly entirely radio silent since the SoD backlash, patches are few and far between and we have no idea when this game will even be playable online.
Is this the best you've got to give?