One of the newer trends in RPG's is to take the MMO system of assorted people giving you a wealth of quests to do that you will complete in order to unlock the story. The more you do, the more you comprehend.
KoA takes it to a bit of an extreme. The game is insanely long and, eventually, you have to quit and just minimize what you're doing. After 76 hours, there were still several dozen quests and tasks I simply didn't want to deal with any longer and just completed the game and its first DLC pack. There is such a thing as a bit too much content and this game flirts with that.
You are the Fateless One, the one person who is able to shape him/herself into whatever you wish to be. You want to use magic? Fully functional. You want to hack and slash? Also effective. You want to do both? Very effective. It's one of the few games that does not penalize you for not engaging in min/max gameplay. I focused on might and magic primarily and created a very potent character build.
It is also somewhat baffling that in a game with so much loot --- and it really is laden with loot --- you are given a fairly small inventory. There are are so many weapons and armor sets that it is sad that you, likely, will not be able to get more than a tiny number of them together due to space limitations.
Now, this has been a pretty negative critique thus far, but keep in mind, I played it for over 76 hours. That alone shows that the game has some good stuff in it. And the combat was more than functional. It was actually one of the better combat systems I've seen in a while. On hard, some strategy, blocking, and dodging is a necessity to move ahead and handle some monsters. And, yes, there is a significant difference in enemy difficulty in hard than in casual. In hard, they aren't just damage sponges --- though, yes, they are major sponges --- but they are also far more aggressive and you will have to deal with multiple attacks at once frequently. The final part of the game is one of the more challenging battles I've dealt with since it is constant over a long area to get to the final boss. Tragically, the final boss is absurdly easy --- possibly the easiest in the game.
I actually was grateful for Achievements here because, as something of a completionist, getting all the Achievements allowed me to ignore a ton of quests I simply did not need to do. There is a level cap (though by the time you hit it, you are really, really powerful). There are a ton of things you can invest your skills in, all with some benefits. Lockpicking is always helpful. Sagecraft becomes really helpful when you get to the later stages of it. Ditto blacksmithing. Persuasion can definitely make some conflicts markedly easier.
I do recommend the game. It is a beautiful game with a nice visual style. It feels suitably huge and the environments are varied. You have tons of leeway to develop yourself in any way you see fit. It, tragically, launched in the same time window as Mass Effect 3, so it has that problem, but it is well worth your time and money.