Amazon released the original Kindle back in 2007. In the years since, the devices have managed to peak, go mainstream and then get largely replaced by tablets and smartphones. Amazon's first Kindle was 7.5 inches tall with a high-contrast screen, an SD slot for additional storage and a 3G connection that permitted users to access its "Whispernet" data network to download books on the go. It sold out in less than six hours, quickly cementing its position as the leading e-reader on the market. About two months ago we asked readers to look back and review the first-generation Kindle, more than a decade after its release. Here's what they said about the device, from the hardware to the book selection.