I was highly skeptical of this product, but after using it I've found it to be very successful. I've caught several plaice and small bass with these, especially when paired with a rag worm scent spray. The trick is not to leave them in the water for hours without respraying.
I would say it is much (much!) better than freeze dried rag, though not as good as fresh. But I'm too old to go digging for worms anymore.