It's amazing what a little PR can do to a product that was originally opium based and is currently the sweetened face of an enormous evil beverage empire.
But that is neither here nor there. Conceptually it's tied together much better than all of your other work. It also has a very consistent quality that I like. I think if you experiment with that style a little more you can make it very striking. This whole vector art thing that is falling into trend these days is, I would bet, going to create a backlash to that sterile form of art and I think people who can create very rough, organic, and concise imagery are going to be a premium. So work with it, I suspect it may be very valuable to you in the future. Try finding simple brush strokes that create certain textures. Just like a gesture, nothing more.
As an advertisement it's not bad. I think it would work better in the world market than it would here. I also think that the point of diversity that your teacher made is a good one. Even if the Coca-Cola company wasn't trying to con the world into believing that they package dreams in a bottle (for example, how does a drink with no nutritional value that has half the carbs "set you free?"), maintaining an element of cultural diversity is important. It's one of those things that people don't notice unless it's not there. I think a lot of minorities just gloss over the ads that are only for the clean-cut white folk. I know I do. Or at the very least it is a barrier to generating interest.