Yep, I have it it's great to read, VERY interesting letters, most of them pretty long.... they give an excellent portray of Tolkien as a person and also the political situation during his time and stuff like that... and loads of fascinating material about Middle-earth because he answered loads of fanmail with quite long explanations.
It's also where for example the basics for the reconstruction of the quenya noun grammar can be found
Yea, you sometimes get the impression that they have no idea what LoTR is about and that somebody just told them the names about the main characters, and the rest -
... yea, the letters have some of Tolkien's comments on strange criticism... also his commentation of a planned film of LoTR quite interesting to read
It answers some of the main questions that are asked all the time in the forums