Pretty good.

Its a good application for the trumpet enthusiast, the fingerings are all there. The "blow" feature is there mainly for fun, its kind of impossible to tell what open note you plan on blowing to next. Other than that its a neat little trumpet app, 3 bucks is a little steep but Id say its worth it. Good programming quality. Very nice iPhone emulation of a real trumpet.

Dan teh man ^^ about iTrump - '2-inch Trumpet' with Trumpad