Awesome job! Some minor issues, if I may:
In the future, or if you plan on taking this guy further, I would suggest working on the textile density, all the UV space seems to be in the head, which don’t get me wrong is warranted in almost every circumstance, and its taking a lot of the map detail out of the rest of the body. For this kind of creature, I think the textile density should be relatively even the whole way through, with some priority put into the head. Also, I’m seeing some sort of texture seam/Y channel inversion in the left-most horn; I’m not quite sure what it is, but I’ve seen many pics floating around the internet that may suggest its something to do with the Y channel in the normal map? If anyone else has a better/correct answer, or can word it better please do so. More or less these are just things that I wish I had been told the first time I made a low-poly game model, and seeing as how this is your first I’d say you did a damn fine job. Your work is awesoooome!
Oh, and by left-most horn I was referring to the first image posted, crappy internet didn’t load the second image before I hit the reply button