The concept isn't bad but the thought of curling up under what looks like a nylon sleeping bag doesn't appeal, I'd prefer fleece or wool much snugglier!
I've got one although not that sort of pattern. It sits nice and neatly on the back seat of the car, ready for the little granddaughter if she wants a nap on long journeys
I too have fleece throws that fold into envelope style covers for the little ones, as with anything like this - the zip is often the weak point of the design.
At first i thought I wouldn't want one, but thinking about it, I keep a blanket in the living room for me or OH to sleep under when he snores. It would be nice to zip it up for daytime.