There were a lot of things I liked about this, but also many things I didn't, so I think an overall of 3/3.5 stars is fair.
I really liked Penelope's dry humour in the beginning and her character, although I felt some of it was lost in the middle, but then we saw her strength again towards the end. The letters between her and michael as children are a nice touch and hint at their childhood relationship/background, which gives more realism to their connection and why Penny believes Michael to be more than he is currently showing.
I love the way they meet again for the first time since they were children in the woods and Penny's happiness at seeing him again, but then it was all rather cruel for quite some time after that - however I guess this was the story. I get that he was supposed to be a really damaged and bitter person, but something didn't click for me and I felt we had quite a bit of nothingness during the middle of the story with a huge amount of cruel behaviour on Michael's part and a lot of weak behaviour on Penny's part - I think some of this section could have been made better. By the time they actually get into a better state, its the very end and we don't really get to see them interact much at all actually being normal with each other. Even the epilogue, apart from a tiny piece is actually the set up for the next book in the series (Pippa & Cross' story).
The more I read, the more I wanted Michael to have kept Penny's letters too, and although he does, as you see right at the end in the epilogue, its done in a reply letter and doesn't really say much - it felt a little tacked on at the end as an afterthought almost and didn't feel very satisfying.
I do like the whole set up of The Fallen Angel with the four partners too, and they seem quite interesting - but I can't say they drew my interest enough to desperately want to read the next one straight away. I do think I will continue with the series at some point though.
I think maybe I shouldn't have read this so close to [b:Nine Rules to Break When Romancing a Rake|6584134|Nine Rules to Break When Romancing a Rake (Love By Numbers, #1)|Sarah MacLean|http://d202m5krfqbpi5.cloudfront.net/books/1286649993s/6584134.jpg|6777627], as there were unfortunately quite a few similarities between them with the heroine's desire to have some adventure and go to the men's club etc, although I have to say I did much prefer Nine Rules to this story.