This brings back memory's
2 things that catch my eye:
-The water thingy's on the back, they don't really feel like they are a part of the body, in the original drawings, he has some holes/square things where they stick out.
It looks as if they are superglued on.
In case you were planning on doing this, and just haven't done it yet, then nevermind that :p
- His face seems to trend a bit to much towards a sort of wolf head, his nose/mouth seems to be to pointy.
Looking at your reference, the second row, second picture, the whole front seems much rounder to me.
Altough that might be just me, but I do feel like there is just "something" off about his face.