I have never used it myself, but I've heard some people who were quite unhappy with it. It's probably not much different than using rock, really, and if it gets scattered about, well....

I was told it was difficult to get "stuff" out of - leaves, branches, whatever. I would be concerned as to whether or not the coloration would fade in our sun.

I've seen it but never tried it, so I'm curious to see what people who use it think. I just can't get past the smell, it really does still smell like rubber to me, and I can totally see Pagan's point about it being hard to keep clean, the surface is sort of sticky/tacky. Hopefully someone who is using it will chime in. If you give it a try, let us know how it goes! Happy gardening!