My favourite part ? Omitting that Geralt is one of the most dark, mature and charismatic and personal favourite of mine, character of all time, from the books to this awesome videoludic redirection, I've REALLY enjoyed the side quest called "The Secret of Loc Muinne" activable when you reach Loc Muinne, if you had chosen Iorveth as your ally. That part when you reach the Dearhenna laboratory and you have to solve two riddles, where you have to be smart and use your brain, try to trick the golem on the right way without killing him, was very challenging and satisfying.
At least you can use even your mind in TW2, instead of unshethe your sword to left and right, trying to kill little annoying drowners.
That's something surprisingly engaging and unforgettable !