Not bad. The concept is interesting and I've seen worst artwork. I'm not sure if it was the website or not, but it only let me read the first 17 pages. I can't gauge the hook fully, due to being an incomplete read on my part. Is it because I didn't join the site?
I think your action scenes could use a bit of work and the facial expressions could use a bit more animation. Other than that, I think it turned out quite well. I love the scene when they first enter the "frozen" city. The line work is amazing!