Yeah basically what they said. At first glance it looks pretty good.
But the rib lines are definitely off, IMO it looks angled incorrectly with the way the body is positioned and how the chest area should bulge out a little from the body's angle.
Looking at it closer, the top of the muzzle looks like it's at a different angle than the rest of the mouth, as if someone glued the top piece on incorrectly.
And I'm not sure what, but there's something about the mouth shape and tongue position that makes it seem like he's having a gag reaction to a bad-tasting piece of food than being enraged by something.
The claws look cool and I can't see anything wrong with their positioning or detail. The spikes on his back also look really cool but slightly bent / misaligned with the rest of the angle of the body. The gills are a cool effect but appear to need a slight rotation to remain true to the angle of the neck.
Well, that's as much as I got. Happy drawing!
-SG7 ( :) )