I enjoy sniping games, the zoom, the exactness of hitting your target perfectly between the eyes. They are, for want of a better word, fun.
Sniper 3D Assassin gets this part right. The simple zoom and shoot controls work well in conjunction with the gyroscope aiming. And, for a free game, it looks rad.
Unfortunately, it gets unsettling. I play enough games where I kill fools left, right, and center, but gunning down (for example) a journalist because he is near the truth, leaves a bad taste.