I noticed that my 3 month old baby was getting a flat spot on his head and bought a couple of other (much cheaper) pillows, none of which seemed to make any difference. This pillow is great - the baby stays put all night long, it appears to be comfortable, is soft and can be washed easily. Not sure whether it is solely due to the pillow, but my now 4 month old baby's head is looking much better and the flat spot is hardly noticeable! Will continue to use this pillow and chuck the other ones away....
UPDATE - My baby is now 5 and a half months old and after using the pillow for over 2 months, it has gone very flat. Washing/drying it doesn't help. Although it is a good product, it is quite expensive and won't last you a very long time!