Aside from the obvious and glaring parallels to Dresden, I really enjoyed this debut. It is both fair and unfair to draw parallels between the two - Butcher has firmly established himself as the king of urban fantasy, and seems like anything in the genre since is at least similar in some way. Iron Druid is similar in a LOT of ways, but that's not an inherently bad thing.
There are a lot of plusses to this - the most glaring is that Atticus is sincerely lacking in the obnoxious, white-knight moral bullcrap that Harry Dresden churns up so much. None of this "omg a damsel in distress" BS, none of the arbitrary moral guilt after killing some random evil. Atticus just does his thing, kills when needed, moves on. In addition, I found Hearne's writing very approachable, and as a 27 year old male, his style of using terminology and tech references that are relevant to me are appealing. And while Dresden has some funny moments, Iron Druid had some much funnier times, and more consistently, though a few DID feel a bit forced.
In all, I liked it a lot. I can't give a 290 page book with some flaws a 5-star, but I've already ordered the next couple books in the series and look forward to reading them. I was put off a bit by Atticus' apparent overpowering, including the ability to seemingly kill anything without any real issue (he killed two of the most powerful gods like it was nothing, essentially). He's immortal, has no end of energy, can regenerate, etc. It's interesting in itself, and he feels significantly more powerful than our buddy Harry Dresden, but I'm interested to see how that evolves in future novels.