The Son Of Neptune
If you are a fan of the Percy Jackson books, not the movie as it's not very good, then you should definitely give this most recent series a shot. It's the same universe, yet this time it is dealing with the Roman gods. This is the second book in the series and I especially like the way that the author develops the plot and how it slowly unfolds revealing more and greater layers.
The only problem with this book in my mind is that if you aren't familiar with the other series you might be a little lost in some of the references that are made back to older books. Don't get me wrong, the characters stand on their own and the plot is strong, I just feel that some of those references are better if you have the background.
Overall, I feel that this book is great for anyone who likes epic plots with lots of twists and turns in addition to a sprinkle of humor thrown in. He makes the everyday world seem like a cover for some of the most imaginative and well thought out mythical relations. For example Amazon.com being a cover for real Amazons. Good stuff.