I would correct one thing, there is a clear parry system, which will block the incoming attack, and knocks the attacker off balance. The trick is that it doesn't work for all opponents (mostly humanoids with 1h weapons, and some 2h), and you also have to time it. It's pretty essential when fighting enemy who use shields. If you just hold it down, it becomes more of a block and just prevents or reduces incoming damage. If you time it, it knocks them off balance and they drop their guard for 1 or 2 free attacks.
I found the combat in The Witcher 3 to be decent, though I won't call it a great combat system. It's definitely gotten better over the Witcher 2. You also get 2 dodge options, one to stay within combat range, and doesn't use stamina, and another to leap much further, and drains some stamina.
Then you get the signs, which can be a big part of your combat or not, depending on how you build. I liked to use signs, as it does add depth to the combat, so it doesn't feel like you are just randomly swinging your sword at everything, or going dodge crazy. Aard gives you the ability to knock weaker enemy down, and stun stronger ones. Weaker ones often become 1 shotable once knocked down, bigger enemy will drop their guard for a moment, to allow you to attack. Igni is a fire attack, which can be very potent against some enemy, while others it may only serve to lower enemy armor and cause them to drop their guard like Aard. Quen is a shield, and when upgrade can be an active shield which can be used to knock back opponents or to heal yourself. Yerden is more of a slow trap, and can be used for damage, but at higher levels, the damage becomes low, and it's slow to set one, so I stopped using it. Axii is mostly for mind control. I never used it in combat, but it can put enemy to sleep, or make them fight on yourself.
All and all, I'd say the combat is better than Skyrim, but not as good as something like Batman AA.