If you haven't watched the movie yet, but you do like comedy, go out and buy or at least rent it! The fact it won, the animation Oscar, is not a coincidence! I haven't watched many other Wallace & Gromit movies (in fact, I think I only watched one other), but the humor is very distinctive ... and some would also say very British. In a good way of course!
The story will only be an excuse for all the jokes to come, but although it's not the most elaborate one, it still works (by the way, my niece did guess see one of the big surprises coming, I didn't, Kudos to her ;o) ). I do think, that after you watch this one, you'll go out and seek the other W&G movies, that are out there. Have fun!