It's really well written, the characters are great, OC's like Meciel and Amanda (she appears so little in the Dresden Files, she might as well be an OC) are great, Dumbledore is, as mentioned, indeed the best Dumbledore written in any story I've read so far and the fights scenes and the combining of the mythologies works really well.
Admittedly, Harry is a jerk but then again, him being a jerk has negative consequences. There is really no bashing in the story which is a huge plus. Hermione gets treated a little rough but that's less the author hating on Hermione but rather the more believable clash between those two opposing personalities.
One of the better stories of fanfiction and definitely one of the best series. I am really exited to read his his newest story.