This is a fun book that posits that math and computer science are the doorway to magic, and that some equations are a little too dangerous for public consumption. The magic is borrowed directly from Lovecraft, including a reference to Miskatonic U.

It's fun light reading, though it's not as good as his first books, Singularity Sky and Iron Sunrise. I'm pretty sure those two were written later than The Atrocity Archives, and it shows a bit.

One problem with this book for general readers is that there are quite a few jokes that are only accessible to geeks like myself, about things like computer science and tech support. While you can still enjoy the book without any background in those areas, you'd probably be missing some of the best humor. On the other hand, SF&F is for geeks anyway, so he's probably right on target.