In a nutshell the books are useful for reference. You can get the tunes from the Full English, and details of the singers from the 'Cecil Sharp's people' website.
A lot of Reeve's input is very dated thinking. To be fair the books were published in 1963/4 However as an example, Reeve's explanation of 'The Foggy Dew' is over researched nonsense.
In respect of the words contained my view is go to the original and make a comparison and see which you like best if you are a singer. Other than that the books are a starting point for further research, but I personally paid under ten pounds for each book on Ebay.