Yes, it will shrink. I tried my first quilt with it without first pre-rinsing, spin and dry in dryer of the batting. After I washed the finished quilt, I saw that it shrank more than the other battings I've used in the past. Battings I've used in the past includes 100% poly, 100 % cotton and fleece.
So I'll rinse, spin and dry before I use it. It does have a nice feel to it, too.