I watched the show first before reading the books and I glad I did. It put a lot of locations and characters into perspective for me and game me some image to build on when reading the books. I can't wait to see the ship battle too and sunspear. I can only image how it's going to play out. It's gonna be so awesome! Imo mila kunis would be great as one of the sand snakes.
@mikey87144: I don't know if you are being serious here...if you are and this is a legitimate question, then the books are faaar more in depth than the series. I am currently halfway through book three part two and I can say that I haven't been so immersed in a series for a while. Yes, the books are long, but they are not difficult or boring to read - just the opposite. Like one poster said before, if you watch the show first, you won't be able to conceptualise the characters, which, to me, would be a loss.
I do think though, that the most poignant moments in the book (at least the first one -haven't seen the second series) are done so so much better in the book. All this being said, I feel that what you should do is to read/watch them concurrently. Therre is A LOT of mythos in the plot and context that I found quite hard (for the first book at least) to follow - I found this all explained a lot clearer in the series. So, unless you have a friend who is able to explain any questions about mythos or characetrs, I would say to do them together with a focus on hte book (i.e. reading the book before you watch that particular episode).
Definitely read the books first, it gives you a real nice backstory for the show. I have watched with my friends and what they found confusing I understood right away, you recognize various characters and settings right away. Also the books have maps of cities and the world and that gave me more perspective about the world. What the books did for me was that they kinda set up the show so that I have gotten way more out of it than my friends who have not read the books. Read first, watch later