Halo was pretty good book but it included some things within that I couldn't agree. As a atheist the religional subtext was really annoying, expecially how it showed in the book. I got the feeling from the book that you're good if you believe in God and do as he has said, and that you're bad if you don't. It was really black and white, which was really annoying. The book and character's itself was really black and white. It's not realistic because life isn't black and white.
The plot was pretty predictable which took most of the trilling away. Character's were okay but they didn't have much depth in them. They were unfinished. When I was reading it, I got the feeling that writer must have been pretty young when she write Halo. After reading I found out that she was pretty young. Being young published author isn't bad thing but in Halo it showed so much that it distracted reading - expecially when I felt more mature than books plot or any character. I recommented that you think twice if you want read Halo in case if you don't like books for young adults. I'd say that Halo is pretty much for religious people and teenagers - for them I recommend it but not so much for people who isn't religious or whose doesn't enjoy books for teenagers.
Halo's idea was good and some character's interesting, like Gabriel and Ivy (for their long life and everything they've experienced), but implementation wasn't so good. Most of character's, expecially Bethany, were unfinished. Maybe Adornetto has deepened character's in sequel's but in Halo most of character's felt unfinished - like they would've created in hurry and that they were just made for stereotypies.
Halo is readable book and if you like religious subtext and books for teenagers, it could be pretty good for you. But to be it wasn't special or that good so I'll give it only two stars.