I have two Kindle e-readers, one of which I bought for my son to use. I have recently purchased a second book cover. This time it is the lighted one. Here's my review.
The lighted cover costs about US$60, minus shipping. The non-lighted one costs about US$40, but it is no longer available from Amazon. They look almost the same, except for a pull-out LED light, which draws its power from the Kindle itself through the metal hinges (very clever).
Here are the significant differences. First, the lighted one is about 50 grams heavier than the non-lighted one. It weights 233 grams. The Kindle itself weighs only 225 grams. Second, it is actually slightly thicker, especially on the bottom cover where it houses the LED light (see picture).
Bottomline: The lighted cover is not bad because it enables me to read without ambient light. The light doesn't glare, therefore I am quite pleased with the quality. It would be perfect if it weren't so heavy. Perhaps Amazon might consider making the next one out of lightweight synthetic material instead of leather.
(Concerning the weight, I never thought of it when I was carrying the unlighted cover Kindle, which was only 50 grams lighter. This one does seem a little heavy at times. I wonder how anyone could carry the iPad for long when using it as an e-reader)