Basically me and all my friends I know that play Heroes 5 have totally given up on multiplayer, it is simply not stable enough and it doesn't really do any proper correction when something goes wrong.
Not to mention the AI is messed up in multiplayer.
Yeah, there are fewer errors, but then again there are still quite a few players out there who likes playing against the AI or coop against the AI (or against eachother with AIs)