Really I actually thought combat is the one thing TW3 looks pretty bad at. Even if it might reflect on the style of writing it doesn't in the least fit the setting.
Actually it does. Read the books.
Geralt has superhuman strength, speed, agility, endurance, and reflexes. All Witchers do, as they undergo magical alteration when they are young that turns them into killing machines perfectly designed to deal with the monsters they are designed to hunt.
Even so, the melee combat in the Witcher games is much less over-the-top than what we saw in Dragon Age 2. And judging at least from the clips we've seen of both TW3 and DA:I, DA:I's melee combat looks to be more cartoonish as well.