If your mattress is just a normal mattress and you like the feel of memory foam this is a good product for the price. One thing that I like about this foam is how "thin" it is, so you don't get stuck in the memory foam. Also, it might be half an inch to one inch smaller from each side based on your mattress size (maybe bigger too?). So check the dimensions before you order.
Keep in mind the product does need to be left open for a while to expand and it doesn't smell pleasant during that time. So don't put it on your mattress right when you get it. Let it sit for a day or two and then start using it.