Underwhelming. The mini-story they are trying to tell is vague at best. No additional dialog outside of the Hammerhead talking to you briefly, and a few data pads. If played during the normal course of the game you might not notice this as much, but on it's own, it's not particularly well done. But hey, it's free, right?
edit: Forgot to say that this DLC really feels like a test bed for vehicle exploration in ME3.