I don't think it's awful. The Q1 shamb has a big gut, so it's a reasonable interpretation to make a high-poly shamb a bit fat.
The claws...um, are cool, but they're really not claws. They're bony fingers.
It's the mouth, though. That's the problem. Those teeth are wrong. As the guy posted below the pic, they're chisel teeth i.e. herbiverous. Not monstery and certainly not like the original's teeth, which are the clearest part of the skin.
Perhaps he was basing his interpretation a little too much on the model Speeds linked earlier:
http://www.geocities.com/leedlebeetle/QK_marine_shambler.jpg