I used Fusi-Boo in a wallhanging and in a baby quilt. It was a pain to get it unfolded, but I persevered. I wouldn't use it for any quilt that's bigger than baby size. The batting itself is fairly thin, and got nice and soft and crinkly after I washed my quilts.
You need to really steam it well to get it to stick. I tried to use it again on a 3rd quilt but I couldn't get it to fuse, even though it was fine for the other 2 quilts.