Hmm. I may just look at one as a personal Christmas present. Trying to read my Kindle Keyboard with just a Coleman LED Lantern during Hurricane Sandy's power outage was not fun! I had the leather cover with the extendable light, but it ended up screwing with my original KK and I haven't used it since. The backlight seems useful. As the only review on this thread is from someone who doesn't appear to have one, I'll take that as a good sign.
As for ads/no ads, I gifted my grandfather a Kindle w/ ads a year or so ago and he only noticed that it had ads three months ago.