Well, I haven't played the Witcher 3, only the first 2 and I found the combat absolutely terrible. Playing that game felt like a chore. Don't know if things have changed with The Witcher 3
As for Lords of the Fallen, I can easily say that it's worth its current reduced price. The game is great and very underrated. It's a lot like a Souls game, only a bit better in terms of combat. Souls games feel like budget games to me. I also feel like Lords of the Fallen is much more beautiful than Souls games, though much worse than the Witcher 3, of course.
I say do it. Trade in the Witcher 3 and get Lords of the Fallen. If you're anything like me (at least we both don't like the combat of the Witcher 3), you won't regret it.
But keep in mind that the game is not very easy. If you don't like difficult games, you should probably not bother (though, having said that, I don't like hard games but I liked Lords of the Fallen).
