Well, the one review of the small set on Amazon said the pieces were too small to use. I always think, with something like this, it's better to start with a large size first.
The only advantage I can see to these things is that you can make fancy puffs with them if you are willing to take the extra time to use the clips to fashion the puffs. There would be no reason to use these clips to make regular puff quilts.
One thing I learned by making a puff quilt (biscuit quilt) is *not* to pack the puffs too tightly. My baby quilt ended up being hard instead of soft because I had packed the puffs too tightly.