After trying my knee pillow for about a week I can say that awake-me likes it and finds it comfortable, but asleep-me hates it.
When I'm awake it feels like it helps my hips relax a bit more. But I keep waking up with it on the floor, even though it's got a strap.
Which means asleep-me has removed the strap, lifted my 20 pound blanket, threw it away and put the blanket back on. I don't know why asleep-me dislikes it so much.