Review (4/5): Meh
It does a decent job but it doesn't seem to give my hair the lift or body of the typical diffuser. I use it when I travel because of its collapsible feature, which is great! But I definitely prefer my regular non-collapsible diffuser when I'm at home.
My hairdryer gets extremely hot and I've noticed that the center piece inside has gone missing and one of the nubbies had to be glued. I've only used it a few times but I'm thinking it might not be a quality issue. More likely it's because my hairdryer is hot as hell.