I have used it a number of times. I generally don't on kid quilts, where I generally prefer flannel or corderoy, but I included crayons with one recently with instuctions on how to customize the back.
I like showing off my quilting, which muslin does. I buy Moda muslin by the minibolt (10 yards), so I have a good quality with an excellent 'hand'. I also use the Moda for printing, so I don't worry about having some left over.