Starting off, for a first, this is quite amazing. Let's pick it apart now.
Goods: The muzzle was drawn greatly, and the head too. I liked the markings in the back as well, but I feel they had no texture to them.
Bads: Nothing overly bad, a few noticeable thing though. I feel like the limbs are a bit too wide and very, very slightly too long. Again, the back marking accent it well, but it lacks texture. The way the tail connects to the rump is ackward. Also, again, no texture on the tail. It's like if you dipped half a wolf's tail in white paint. It would make an impossibly smooth line. Fur could be viewed as smooth and connected, but here's no impurities. The paws look weird too. Not the shape, the colors don't click for me personally. If you were trying to make face markings, same with the consistency and the texture. If you were trying to make whiskers, (no offense) then you horribly failed. Whiskers can be used to convey emotion and such, but they are not impossibly thick like that.
Overall, this is very well drawn, and has lots of potential as well.