First, there's a boldface lie on the cover. When you see that on a dictionary that usually means 500,000 words are defined in the dictionary. But I counted some pages and estimated the total number of words in the dictionary. This dictionary doesn't even have 500,000 words even if you count every single word in it, let alone looking for 500,000 definitions or entries. The editor of the great Merriam Webster's Collegiate Dictionary once told me there are only a million words in the English language, and even the mighty Merriam Webster's Unabridged dictionary doesn't have 500,000 entries.
Any good dictionary has explanatory notes.
It's also hopelessly outdated and its organization is bizarre at best and totally wacky at worst. For example, it has an entry for Presidents Warren Harding and William Mckinley, but none for George H.W.Bush, Bill Clinton, John Kennedy, Thomas Jefferson, FDR or Teddy Roosevelt. It has an entry for the abbreviation of Illinois, but mysteriously omits New York, California, Pennsylvania, and every other state we checked. One other small point. It not very good at defining words.