This series of "Unfinished Tales" is simply an indispensable marvel at any Tolkien fan or lover of Fantasy. Christopher Tolkien has done a remarkable job in editing and shaping of the unpublished writings of his Father. I suggest you read before The Work of the Master, ie the Lords of the Rings, as this may be to avoid you getting lost in the wealth of these Tales. You'll be able to understand many things that you will not be raised in the first reading. In fact these books help to know a little (lot) more about the legends, people, characters, Dynasties, kings and all peoples of Middle-earth and mythology founded by Tolkien. A bit like a historian who you reveal all the secrets of civilizations we have been through, through exciting, epic tales and incredible beauty narrative.
In short, if you are a fan or Faerie Fantasy you can not pass up these three works, just as you can not have not read The Silmarillion. And for the price collection Pocket would be unthinkable not to read all three!