Got mine yesterday with the airlock kit. Overall, I'm not really impressed with the Brew Demon. Mr Beer definitely seemed to be higher build quality. I also don't really understand the plastic/foam insert on the top, feels like it would absorb liquid and harbor bad stuff. The lid doesn't really feel like it screws on well. As for the airlock kit. It's a rubber gasket that goes in the lid (right now I'm assuming it's supposed to replace the foam one and not just go over it). There is also a drilled bung that will fall in the fermenter if the airlock is not inserted. Basically the airlock makes the bung "fatter" so it won't fall in. Face value doesn't really leave me thinking "wow". We'll see how it works as a fermentation vessel though.
Not too upset since I got it for the novelty, but Mr Beer does hold the advantage in my mind so far.