Shiurim in this topic
Whether the Kabbalah of the Arizal is to be accepted in its entirety:
According to the Alter Rebbe's letter printed in Beis Rebbe, the Vilna Gaon held that only a small part of the Arizal's Kabbalah came from Eliyahu HaNavi and the rest from the Arizal's own great wisdom, so that one is not bound to accept all of it. The Rebbe notes that Rabbi Chaim of Volozhin, unlike his teacher, accepted the Arizal's Kabbalah in its entirety — just as he departed from the Gaon on the tzimtzum (IK 10227).
See also: Kabbalah – Tzimtzum: literal or not; Kabbalah – Studying Kabbalah.