I read my Kindle on the chairlift while skiing--put it in a plastic sandwich bag and you're good, except with thick gloves it is difficult to push the "on" button, especially when the Kindle is in the bag. In a blizzard, it's hard to read a conventional book because the snow gets down in the crack between pages.
I've never had any problem with this daytime activity even when the temps were down to 5F, but out camping has been another matter. If the Kindle is left in sleep mode and the temps are below freezing, by the morning it will either say that the battery is low, or it will be completely locked-up. I've tried warming it over a stove, but to no avail. But when I charge the frozen Kindle, it recharges quickly, leading me to believe that it is not the battery that was drained, but rather something in the operating system that reacts poorly to cold weather and shuts down to protect the device. The solution is, of course, to sleep with the Kindle in your sleeping bag.
There are some things I miss about paperbacks: you can use them to start fires, swat mosquitos, and give/lend them to others. Also, with a Kindle you can't write snarky comments for the next reader to see, such as: "He escaped through the back door of the Pinto"--Pintos never had back doors.