"Weak demons"??

Nah, that’s not true. There are actually no problems with wood or ore. Just take Daleb, who isn’t overpowered, but simply a good hero with a ballista. Jumpers actually risk getting a double counterattack only in the endgame, and there are usually no problems with this on neutral creatures. And don’t forget how demons consume mana and also give it back to the hero – because if you develop the demons properly, they will crush everyone with a single berserk and subjugation, and also with temptresses. No, you clearly haven’t played demons very well, otherwise you wouldn’t judge them like that. This also applies to everyone here who thinks that demons are just bad chaos creatures. 300 mana for darkness, and your hero has 0 – what will you cast? Take Daleb or Marbas, and you’ll see that it’s very, very difficult to defeat demons in a real game.

Added 1 minute ago
What do you think about a surprise attack – teleport with increased initiative? That’s just awesome – consider that all your archers and mages are dead.