I've got two of them. However, I wouldn't recommend them. Two reasons:
1) Material is thin. Thinner than any other muslin I own (or have owned).
2) Customer Service. This was last year. I ordered two painted muslins from them. One was shipped immediately, the other was on back order. I waited a month and finally asked for a refund (via phone). They said a refund was no problem. Almost a month, and several calls/emails, later, I still hadn't received a refund. Then I received an email stating that my muslin had shipped. Unfortunately, they shipped the wrong one, a solid black one. I decided it wasn't worth the further hassle to return it and argue for my refund, (which is probably their plan all along) so I kept it.
I'd suggest looking at other brands. There are plenty out there. I currently own BG's from Westcott, Silverlake, Denny and several other brands. All very nice.
BTW, if you're just looking for solid black or white, you can also just buy raw muslin at a yardage shop. Even WalMart carries it.