John Ball-A Treatise of the Covenant of Grace

[Mayflower]

I read that John Ball-A Treatise of the Covenant of Grace is a Facsimile Reprint from the 1645 edition. Does anyone has this book, and is it difficult to read, because it's old gramma ? Any thoughts or reviews would be helpfull ?

http://www.peterreynoldsbooks.com/si/090004.html

And what does this work added if you have already Witsius ?