I used it once on a millennium (2,000) piece quilt. I hated it! I found the seams extremely bulky and hard to quilt through. (It was the 1" fusible grid which finished to 1/2" squares). I found it difficult to get accurate 1/4 inch seams. This is the grid that you fuse the fabrics to the grid, fold on the line (right sides together) and sew your seam. The intersections between horizontal and vertical seams were nasty to quilt through and I had difficulty making the intersections lay flat. i won't be using the fusible grid (any size) again.
This is just my opinion.