There are many different varieties of sea salt out there.  What makes Maldon unique is its large, pyramidal flakes.  Some people use it for general cooking, but it really shines best as a finishing salt.  That means cook with less salt, but sprinkle salt on the finished dish.  You really get a chance to experience the unique characteristics (primarily texture) of each salt that way, and Maldon has a light crunch that I find very pleasant.