I did use these laundry sheets for several years. Started when a friend and myself got a whole load on special offer at an Ideal World Exhibition. I liked them, as they took so little storage.In hard water area I usually 1 1/2. or, sometimes 2 for each load. Still worked out price-wise reasonable. Eventually, these became unavailable, no idea why.
So then I turned over to the eco friendly ones various of these, I have been using Tru-earth ones for sometime now. Not the cheapest way of doing my washing, but with just me I am happy with them. Again, little space required for storage. I find they wash about the same as anything else. No idea how they would be on really bad stains - I do use very low heat washes mainly as I am still in a hard water area, I normally put two in with the wash.