While the continued lack of physical buttons is a bit irksome, the latest model of the Paperwhite still includes a number of subtle but welcome improvements. The 300ppi, 6.8-inch E ink display on the Paperwhite now has an adjustable color temperature to reduce eye strain, can last for months on a single charge, and has finally adopted the USB-C charging standard, allowing it to top off its battery faster than before. Just like previous models of the Paperwhite, the 2021 version still has an…