I assumed that I might be disappointed with this pillow as 650 fill seemed like it was pretty low. However the reviews were all good so I tried it. It's so much nicer than I ever thought, in short it's every bit of what the company promises it will be and that's hard to come by. 
Despite me loving it I would say if you put it into a pillow case that has a bit of stretch or extra room I've found that maximizes it's fluffiness and support.