I agree with leloar. Totally.

I've always been a book person, so the light novel having a lot of fillers and spending too much time on premise didn't deter me from reading through the entire thing. But yes, I highly recommend that you watch the anime before you read the light novel. Because the anime is more straight to the point.

Tokyo Ravens piles conspiracies upon conspiracies, although this isn't noticeable until around volume 6 or 7. Before that, it just seems like some generic shounen manga that uses exorcism/ Onmyoudou as a plot device, but when the revelations come, you start to realize that everything has a deeper meaning, that all of them are tied by fate and that the deus ex machinas are not really deus ex machinas. The story is very craftly written, and it's probably one of the best light novels I've read so far.

I'm surprised that the novel version doesn't have any reviews yet. As you may know, there was a recent anime version that came out (season one's done!! They're doing more). It starts off really boring in the first few volumes but they serve to lay some solid groundwork for the plot to take off. It also builds a lot of character development. I can't say too much without spoiling this haha. It's sort of like Kekkaishi except it actually does something with the story. The filler chapters themselves create further character development too! The synopsis doesn't do the novel enough justice - it makes it sound too generic. It's sort of similar to Shounen Omnyouji too. I would watch the anime first since they trimmed out the fillers that the novel has. Then I would read the novel afterwards That way you don't get bored too fast before getting into the heart of the plot (around volume two, three) imo.