Youre right, the game plays very well and the frame rate seems very stable by my experience. The only big problem of this game technically saying is the insane ammount of pop-ins... sometimes, even walking I could see strong visible pop-ins happening not so far from the view distance. It may be one of the worst games Ive played at the pop-in aspect.
BUT, the game plays pretty much smoothly, even with a screen full of zombies! The pop-ins kind spoils some of the experience, but sometimes its also surprising how this game handles the frame-rate. And, the general experience is just pure fun! This game is awesome anyway!