No, they're easy to do. But, if you have fine, small, intricate pieces that 1/4" bias tape can't be used, then you have to do extra fine, careful satin stitching with black thread. And, I'm not very good at it. You can see how poorly I've stitched some of the smaller things.
But, check out this page of beautiful patterns from the "Water Water Everywhere" CD of patterns from Paned Expressions. I'm going to go up there on Saturday and buy the CD!
http://www.panedexpressions.com/patterns/water/water.html
I have my eye on that Old World pattern. I'd very much like to do that one.