Twelve South is a company that specialises in making accessories for Apple products - and Apple products only. They are usually well engineered and well designed, and as a result, expensive. Your view on whether or not they are overpriced is likely to correlate with your view on whether or not Apple products themselves are overpriced.
In any case, this surface protector is of excellent quality, soft and supple, but durable, and very comfortable on the wrists/palms. Being slightly OCD when it comes to protecting my (expensive) Apple purchases, I spend a long time researching cases, screen protectors and so on. Although I wasn't happy with the price of this product, I was able to find a good bargain and took the plunge. I do not regret it. The main difficulty is getting the pad to line-up straight and centred on the macbook, but fortunately whatever glue is on the product peels up very easily without leaving any residue, meaning you can peel it up and place it down a number of times while attempting to get it just right.
Overall, an excellent, quality product, although perhaps slightly expensive for what it is.