Do you love moody boys and Greek Mythology? Then Promise of Shadows may be just the young adult book for you. Personally, I could do without moody boys, I'm moody enough on my own as it is. As for Greek Mythology, I admit I know nothing of it other than what I learned watching the TV shows Xena and Hercules in my younger years. Yeah, that's right I watched them, what of it!? But I always get a kick out of reading books that might possibly make me feel 'clued in.' 
 I do think if I would have been more familiar with Greek Mythology I might have enjoyed it more. For some reason I felt as if some of the novelty of the book was lost on me. It was still enjoyable but at points I found myself wishing that all the names of the characters referencing Greek mythology could have been scrapped and different names used instead. That way I wouldn't have felt the desire to go look up the basics of each new greek figure that came into play. 
 So hence I say, if you're a Greek mythology lover this might be a perfect fit. But then how do I really know because I couldn't tell you if any of the references are accurate - but I'm going to give it the benefit of the doubt. *smile* I really dug Tartarus, give me more time in Hell anytime I say...but then I like creepy things. 
 The characters were good but I never felt overly attached to them. I liked the opening chapters with Zephyr and Cass. And the pompous attitude of the gods was spot on. However, there were times I felt like either the characters or descriptions were contrary to what I'd been led to believe, as well as some descriptors were overly used. 
 One point in particular that didn't tickle my fancy was the use of the "moody boy" trope. This is just a personal preference as I've never been fond of scenarios with the moody or bad boy who still ends up with the girl falling for him. Does it happen in real life!? Yes! So it works, it just doesn't strike a sweet spot for me. 
 Promise of Shadows if broken into thirds slows down considerably the entire center portion. It was by no means empty of content, there was definite character building, connecting, things being revealed etc. I just felt like I was wanting during that portion, as if I was slogging through towards the end which picked things up a bunch and ended on a good note. If the premise intrigues you give it a shot, it was definitely an ok read.