The pedal is very unbalanced. Of course it can never be perfectly balanced since the slave pedal must also drive the shaft. But with this particular double pedal, the left pedal is REALLY unbalanced.
It's perfectly good for beginners. For more advanced techniques, I cannot use it. Heel-toe for me is impossible because the pedals have a stopper, a dent if you will, at the toe part toward the chain and you can't help touching it when doing heel-toe, which makes it really uncomfortable.
But fir classical use, it's perfect and you can't ask more for the money