I got a chance to test these out recently and I see myself getting a lot of use out of these. There are a lot of advantages to using blocking mats instead of a big blocking board (or a bed with a bunch of towels spread out on it...)
Flexibility - I have a great blocking board, but the size doesn't work when I make something like a shawl or with smaller items like kid sweaters. It is limited to the 30 x 48 size. With these mats I don't need to pull out the big board when I only need one mat for a small project or I can create one long mat for longer pieces.
Storage - The mats zip up tidily in the case so I don't have to worry about losing a piece or watching them fall from the shelves and make a mess. I can pick them all up with one hand when they are stored in the case and keep them neatly in my yarn closet. (Yes, I have a yarn closet. Don't you?) The set comes with a box of pins, so I can store those pins zipped in the bag with the mats.
Easy measuring - Other similar blocking mats do not have these 1 inch grid lines. Now, I can easily block to the measurement I need.
Affordable - For less than $40 the price is affordable. If you're not a lucky winner, put it on your wish list or treat yourself.