Man, there are some things that you just do NOT want to think about. Internal organs are one of those things. Sure, they're handy to have around for whenever your body needs to do a thing, but they're also ugly, squishy, and secrete disturbing liquids all the time. And that's the first thing this cartoon does right: it milks the inherent yuckiness of our own body for all its worth.
The SECOND thing it does right would be the way that it makes you feel sorry for those very same disgusting little things. Just by giving them faces and putting them inside a man who's apparently hell-bent on completely destroying himself, they become sympathetic and pitiable. They're ugly yet cute at the same time. And in an unsettling quasi-cautionary tale like this, those are the sort of characters you need to use.
I'm not even kidding when I say that this ought to be shown in schools, on Fourth Grade Health Day or whatever. Sure, that's probably hardly what you were going for, but this certainly teaches kids about the awful shit overweight/drug-addicted people go through.