It is not very good for tempo, but, the value of this card is actually insane and I think people might be sleeping on it a little bit.
4 mana for 16 damage is pretty insane. Upgrade it 1 time and its 24 damage for 5 mana…
If Warrior can get past the tempo loss the upside of this card is pretty crazy, not to mention the synergy with Dr. Boom.