The last render is great

My personnal taste :

-For the mouth, you should have put lot more teeth ? only two look strange, perhaps one model representing multiple teeth and good normal map ?

-The tongue, did'nt needed to be modeled like that you could have only made some simple polygon extrude inside the motuh to represent the tongue ? But perhaps you also want to animate the tongue ? (not necessary detail specially if you fight the monster
the tongue details is not needed (only on high detail cinématics perhaps ?)

Anyway great model.
Are you planning a simple game or shooter using it ?