The folks over at FiringSquad have put together an article that compares both image quality and performance between the DirectX 9 and DirectX 10 versions of BioShock, 2K Games' newly released first-person action title.
Judging by FiringSquad's screenshots and performance numbers, running BioShock in DirectX 10 mode doesn't change all that much. Frame rates are almost identical, and the DirectX 10 version's graphical improvements are fairly low-key. The most noticeable of those improvements seems to be soft particle edges, which prevent effects like smoke and fog from clipping through geometry. The DirectX 10 version of the game does add other effects, such as sharper shadow edges and fancier water ripples, but those are harder to spot in screenshots.