It is a fascinating book, and clearly one that is important considering it is quoted in Jude.

As a Christian, I have a lot of theories as to why the Book of Enoch isn't included in the Bible, one of which is I suspect the way the first age of the Earth is skimmed over in Genesis almost speaks of God's embarrassment about the era, as though he wants to draw a veil over it. Perhaps the way one can be embarrassed by the conduct of one's badly behaved toddlers screaming in a supermarket. Genesis 6 almost reads this way: "There were some giants, and things got bad. Anyway, on to Noah..."