I love the Kona Muslin, as long as it's the one by Kaufman! If it doesn't say Kaufman, it's not the same. I think it's about 200 thread count, very smooth! It's the only Kaufman Fabric I've seen at my local Joann's.
The other Kona solids that Joann's carries is not by Kaufman. They aren't nearly as nice as what you can get at the quilt shop.