I used fusible batting once on a baby quilt. It seemed to work OK for that, but not really worth the bother. It seems more difficult to get the layers alined and laid out as smoothly as I'd like, and would likely be almost impossible on a larger quilt.
Since I learned Sharon Schamber's method of basting with a herringbone stitch using tatting thread I've been pretty happy with the results, especially on bed-size quilts. I also use 505 to spray-baste smaller projects and like it a lot!