Firstly, to give a proper critique, i need to know what the artist's aim is? Is it supposed to have such vivid brush strokes? Is it an attempt at photorealism? Do you want it to have the soft impact of impressionism, or a slightly off kilter feel of surrealism.
This is recognizably Thorin, so right there the artist is well ahead of many that aspire to paint. there are good strong colors, but the edges are extremely rough. there are art styles where that is the point, so i cannot say if this is a strong suit or a weak point.
The other thing is the face seems slightly misaligned, almost as if it were slightly mashed and slid a half mark off like soft clay. I'm not sure what methods you use for underpainting, but there are plenty of tutorials for how to keep the features aligned, and yes, even if you know the trick, it still takes ages to get it right. It may even seem that way because the shadowing seems to have gone slightly wonky, totally washing out on one side of Thorin's mouth. I've had this happen, and it's annoying and hard to fix. I know.
this is still a VERY good painting, don't get me wrong, I'd hang this in my house and be very proud of it as is, but you asked for a critique, and so i'm offering things to do next time to help you improve. I hope I have not overstepped myself.
So, vision: well done. clearly thorin and a bloomin good likeness.
originality: well, i've not seen a treatment like this yet, so?
technique: rough, but is it meant to be?
impact: very thoughtful look on his face, and the eyes are killer. yowsers