Yuriko seems to think it makes a wonderful place to sleep; I've woken up at least two nights in a row to find her curled up on it next to (or on top of) my head. For such a small cat (just over 8 pounds), she's surprisingly difficult to move.
I can only assume Y thinks, "This is great! It conforms to me, it's warm, and Mommy's right here! What more could I want?" :)