I think I'd give this book a 2. While I really appreciated the Greek mythology involved, and the building of the world, this book is literally Twilight.
Helen=Bella (but much cooler)
I could go on and on: Matt/Mike, Jerry/Charlie...etc.
I will admit that I enjoyed this a lot more than Twilight, mainly because Helen isn't as pathetic and useless as Bella. I will probably read the second book only because I am very intrigued about (view spoiler).
All in all, it was an easy read. The writing style wasn't exactly my cup of tea, and it did seem like it should have been written in first person at a lot of parts (from Helen's point of view), but it still held my attention, mainly because I liked the Greek mythology idea and the world building around it.