I love OBW's and have made 8-9 of them. The most important thing about them is that you have to pick a good fabric for it. Get something with big prints that are not humungous and have a large repeat (18-24 inches at least), and do not pick a fabric with straight lines as it will be harder to get that flow that you need. Don't get a fabric with too many colors or you will need lots of hexagons to get that flow. Also cutting needs to be at least semi accurate or you will not get the symmetry. Other than that, have at it. I had a friend show me how to do it and I was hooked. If I were smarter, I could figure out how to post the pictures for you to see what I mean.
Have fun, you will be surprised at how beautiful and easy they are to make.