Helps, but not enough
I've had mine a few weeks now.  I like the simple shape and the large hole for the tailbone, and that it's easily carried and moved.  However, for a person of my size (6ft3in / 275lbs), it isn't strong enough at the back of the cushion to hold up.  It's better than nothing, but it sinks down until my tailbone is nearly touching the seat below anyway.  I would need much thicker foam or some sort of reinforcement.
Rating: 2 stars