Moshe Idel's beatific study of ecstatic Kabbalah is nothing short of a Godsend. His two decade plus quest for Ecstatic Union is a study and an expose of Jewish mystical philosophy. Studies in Ecstatic Kabbalah is an integral part of a few books by Idel that deals with the subject with factuality and reverence that reaches in my opinion the level that Hassidim refer to as Zuggin Torah.
Scholars already know this book, all the rest of us can also find joy and revelation in it as well!