I was conflicted about this series. On the one hand I read all three books to the end. Technically, the story was good, even if the magic was a little out there. The world-building was very cool, complex and interesting, and through the three books continued to get more and more interesting. I liked most of the good guys. The end of the series tied up all the threads nicely.
On the other hand, I put a lot of stock in being able to suspend reality and "buy in" to the magic, and I never quite did. Marble boy just did not sit well with me - I could not suspend enough to not be irritated at that. Things like the flaming horse just never quite made "sense" to me. Also on the negative side, there were a lot of long, long battle scenes. It is a fine line when describing battles. Too much really drags a book down to me, but of course others' mileage may vary. I found myself skimming the grand battles, which to me read a little like listening to someone describe a video game, except with endless detailed descriptions of gore. It got tiresome, and I skimmed. I hate to skim. The gratuitous sex did not help either. It was out of place and unnecessary, but thankfully infrequent. In addition, I could not quite believe the great love between Shaella and Gerard. Why would someone like her fall head over heels for a simple farm boy who is seeing a city for the first time? Didn't make sense to me. I thought it would have made more sense if the demon that Gerard became had retained a little more of Gerard and was a little more conflicted.
In the end, it was a mixed bag, but good enough to keep on reading, and good enough that I would read more from this author. There was much to enjoy, a few things that grated, and I was not sorry that I finished, both in a good way and in a bad way.