This certainly reads like a PhD dissertation, which it was. The first third, detailing everything known about Rabia's life, is very beneficial and beautiful. The second third, a general overview of Sufi doctrine, is interesting but offers no particularly unique insight. The third third, an overview of women saints in Islam, is orientalist and upsetting; the sections are incohesive; some are incredibly boring, many are flatly incorrect and harmful. I highly recommend the first third, suggest perusal of the second if you're interested, but would encourage you to abandon ship by the third section.