Well, I do have one small area that's covered with landscape cloth topped with bark. I haven't had anything grow up through it, but a few volunteers from above (a couple of pansies and, grrr, a couple of clumps of grass) have managed to grow on top of it. So it has worked pretty well for me for about 8 years. I think if it's exposed to the light, it may deteriorate like Karen says, tho.
