Best graphics, content and physics in a bowling app: Brunswick Pro Bowling. The only area it's lacking in is online social integration, ie. OpenFeint, Plus+ etc. The last I knew it was $.99 and besides some clothing upgrades and career mode it's nearly identical to the Wii version. In fact, I found this version to control better than the Wii version. Impressive.
Those are the top two -- GB is a fantasy/SF combat bowling game (with all that entails) and Bruswick is a simulation. Graphically, both are top notch.