I have no idea who recommend these to me (that seems to be happening a lot lately, sorry.) But I remember that I was told they were better that Twilight books. Now, we all know I don't think that is hard to do, but regardless, my expectations weren't too high. As is the norm, I didn't know anything about the books going into reading them. I enjoyed not knowing, in the first book, where the story was going. And then once it was made obvious, I found it an entertaining read. (There are no vampires, werewolves, etc - this series is about angels.) I thought the author had interesting views about the war in Heaven and the results of the fall. I don't agree with everything she suggests, but it didn't offend me to read her ideas. I am reading more books with my tablet's Kindle app (did you know you can check out library books through your Kindle app? Genius, no going to the library.) Anyways, that is how I read all these, so I'm not certain how long the books actually are. On the Kindle, they were super quick reads. I read them in between holiday activities. So probably a good vacation trip book series to bring along with you.
And I agree with whomever suggested them, they are better written than Twilight books.