In the DirectX 11: Tessellation in Stalker: CoP, Dirt 2, Unigine and Alien vs. Predator article people mentioned that only our art sample really utilizes tessellation capabilities to improve image quality: "Only one that was a visually significant improvement was the displacement mapping on the roof. That should be a nice improvement over the various surface mapping techniques, bump, normal, POM, etc. that don't do nearly as good a job."
All hail our artists, who created that art asset! By the way, stay tuned for much more.