The book of Revelation is certainly neglected in the church and when it is paid attention it is often misinterpreted. However, I would contend that the most neglected eschatological book in the Bible is found in the Old Testament, Ecclesiastes.
Here are a few helpful articles by some insightful interpreters on a book that most people do not really understand:
http://paulhelmsdeep.blogspot.
http://paulhelmsdeep.blogspot.
https://s3.amazonaws.com/tgc-documents/journal-issues/19.3_Clemens.pdf
http://triablogue.blogspot.
http://triablogue.blogspot.com/2014/04/solomonic-authorship-of-ecclesiastes.html
http://triablogue.blogspot.com/2014/04/the-gathering-darkness.html