I love my Yachiyo! I was initially quite sceptical because the it was so light and the skinny handle didn't look very user friendly. Its not uber soft, but because the bristles aren't too dense it feels very light on the cheeks. The pointy shape probably helps too. I've only had it for a couple of months and it's become the only brush I use for dark and/or hightly pigmented blushes (I happen to be bit of a klutz when it comes to blush and Yachiyo is pretty much idiot proof). I have yet to try it for contouring, but if looks are anything to go by it would be good for contouring too.
re: Unravelling - I'm worried about that too so I'm extra careful when I wash it and try to make sure I get as little water on the handle as possible. No problems so far!
If you like your blushes I'd say it's a good investment. And yes, it is a very pretty brush (I can't think of too many brushes that would fit this description
)