I think there are a lot of gameplay details, or strategy details, that are not obvious when you start playing the game. Like how the combat works. It's completely timing based. I disliked it at first. But later on I actually started to like it. In my second play-through I played the hardest difficulty. No visual indicators (a flame on your sword) to tell you when to press for the follow-up attack. But by that time, I didn't need it anymore. I could just do my 4 attacks blindly in the right timing. Also signs are very very important. Basically Aard is awesome. It knocks players and monsters down, which allows you to finish them in 1 hit. If you play Act I on the hardest difficulty, you need to spec into that, or else it's almost impossible to kill the first boss (the Hellhound).
During TW2 I learned how important it was to make potions. Some fights (the boss fights) can hardly be done without potions. I had read a few short stories from the first 2 books. In those books, Geralt does prepare for a fight. By meditating, and taking potions before the fight. So while playing the game, that actually made sense now.
I guess the game has some depth, where you don't see it at first. I remember when I played WoW (as a rogue), I had no idea what I was doing (gear wise) until I hit level 40 or so. And only at level 60 I learned the best ways to do stuff (stunlocking enemies). It took me 3 months to go from 1 to 60 (which was normal back then). I still had fun those first 3 months. TW1 has a little bit of that learning curve too. I hope TW3 has it too. (But tbh, as soon as you get the crafted witcher gear in TW3, it seems the game becomes significantly easier).