According to :
It seems to be great. Cheaper than Pink, more R value, better sound
proofing. I'm in Canada but here is the USA site.
http://199.202.236.133/usa/english.asp

It _is_ great.

There's only two ways it's not as good as fiberglass:

1) You can't buy it in "handi-packs" or rolls, so, it can be a
major annoyance if you're just doing small jobs. Only full size
bags of batts - which are quite big and heavy compared to fiberglass.

Thus, DIYers tend not to get a good chance to familiarize themselves
with it on small jobs, and thus don't think to try it on big ones.

Even the guys who blow this stuff into attics buy batts and feed them
to a chopper/blower.

2) Takes up a lot more room in storage/shipping because it doesn't
pack as well into bags as fiberglass - so you have more and larger
bags of Roxul for a given job than you would with fiberglass.

Ie: more trips to the homebuilding store.
Ie: Always in the way if you're trying to store them inside the building
you're insulating...

Still, I'll never use fiberglass again...
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.