The Kindle Battery
First and foremost, Kindle is an exceptional product. That being said, the battery provided for it, is not. After less than three months of moderate use, the battery that came with the Kindle went from working great to flat dead. I would definitely recommend that you buy at least one extra battery to have around just in case you find yourself inconvenienced by this poor product. Fortunately for us, the pricing on this battery is fairly low. Hopefully, the manufacturer is looking into this and will be providing better batteries down the road. {ssintrepid}

Don't leave home without it
I travel a lot (20 days a month or more) and always travel with my Kindle. Even though the Kindle's battery will last for several days, it seems to run out at the worst of times (like on a 4 hour plane ride). I carry the charger with me but this extra battery has helped me out more than once. I am giving it four stars due to the fact that it doesn't just slide or snap in, like most batteries do now. Still, I highly recommend it for anyone who owns a Kindle.

excellent-easy to install!
THE KINDLE BATTERY WAS SHIPPED VERY QUICKLY AND WAS SUPER EASY TO INSTALL!
GREAT TO HAVE A BACK UP ON HAND! I'D LIKE TO BE ABLE TO CHARGE THE BATTERY DIRECTLY WITHOUT PLACING IT IN THE KINDLE ITSELF...IS ANYONE AWARE OF A CHARGER I COULD BUY WHICH WOULD ALLOW THIS?

Short Battery Life
I don't consider having a swappable battery a feature - as much as a common sense engineering decision. I can understand to some small extent why the iPod doesn't - as they are shooting for extreme size reduction. However even in their case - it was a mistake.

The issue with the Kindle battery is that they die too fast - I'm getting 3-4 months before the battery fails to hold a charge - I just ordered two more because my last one after charging all night held the charge for almost 15 minutes - not useful.

I suspect this is either very poor quality control in the Chinese made battery or a design flaw in the charging circuit. In any case Amazon really needs to look into this.

Most annoying feature
I bought a replacement battery and it may prove useful BUT a longer lived battery is badly needed. When I connect to download, I can see the charge decreasing while I wait! Otherwise, in the course of ordinary reading I don't get much more than 4 hours (estimated) . The replacemant battery performs the same way. A longer cord on the charger would be helpful.