Tessellation for this game, Rockstar implements Phong Tessellation to help smooth out rough edges on people and vehicles. The idea is that instead of the curvature of a character's head having obvious rough edges, it'd be smoothed out with the help of phong shading.
As we discovered, however, the effect that this tessellation technique has in-game is minimal at best. Here's a comparison shot:
In all of our tests, we found that tessellation did little more than "bulk up" character clothing - something that's almost non-distinguishable unless two images are looked at side-by-side. In talking to NVIDIA about this, we were told that the biggest differences would be seen in close-ups of characters, such as around their ears or head. However, getting close enough to a character to see a difference like this is easier said than done. There's no camera zoom in the game, so where the differences stand to be seen are in cutscenes.
For a better example, I recommend downloading this archive (400 KB, JPG) and view the included before and after images full-screen. When flicking between them, the differences with tessellation on are noticeable, but are not necessarily "better". In some cases, I'd say tessellation makes characters look even worse. There are exceptions, however. In these shots, Max's hands look far more natural with tessellation turned on. It's the rest that's debatable.