Not only that, the health multiplier for monsters per additional player in co-op games is lowered, being a flat 75% regardless of the difficulty levels, compared to 1.0.3 that had a scaling system of 75/85/95/110%. This means in co-op games, sending hell’s minions to where they belong are far more manageable, where it delivers more rewards for a co-ordinated group with a higher farming efficiency compared to flying solo.
The gap between normal monsters and Elite packs (Champions and Rares) will also be shrunk in Diablo 3 patch 1.0.4, making it more challenging when you go up against normal monsters, while Champions and Rares will be a wee bit easier to handle, although they are still proven bruisers in any encounter.
There will be plenty more changes coming your way in Diablo 3 patch 1.0.4, so you might want to check out the full details here.