Apple has yet to release any official numbers, but early returns on its new iBooks textbook store are looking pretty promising. According to Global Equities Research, more than 350,000 textbooks were downloaded within three days of the store’s debut, along with some 90,000 downloads of the iBooks Author platform. As All Things D explains, Global Equities Research used a proprietary system to compile these numbers and hasn’t revealed much about its methodology, but its figures, if accurate, would certainly mark an auspicious beginning to Cupertino’s latest “reinvention.”