I LOVE LOVE LOVE my Kindle. I got one for the same reason...house overflowing with books.
The battery life is excellent. I read every day for an hour or two and leave it on (with the screensaver). I have to charge every 1.5 weeks or two or so. That's without the 3G running, but really you just surf for half an hour or so if you want to buy books and then turn 3G off. I've had it for almost a year with no probs. I have the Kindle 2. Haven't read anything about the new 3rd gen.
p.s. I found a reviewer's comparison on Amazon.
http://www.amazon.com/review/R2YVZNK...R2YVZNKUMWGYJ4
First, reasons why we prefer the kindle over nook:
* Page refresh speed
Kindle 2 was twice as fast as nook, Kindle 3 is slightly faster yet. However, I read a whole book on the nook and didn't find page refresh to be so slow as to be annoying. You get used to it, and automatically develop the habit of pressing the page turn button a second before you need it.
* Navigation speed
Here is where the kindle has a huge advantage. Moving the cursor around the screen (e.g. to select things) is way, way, way better on kindle than nook. When you use the rocker button (on kindle 3, or the joystick on kindle 2), the cursor moves almost immediately. In contrast, when you use the "virtual rocker button" on nook's color touch screen, there's a noticeable lag before the cursor moves. Plus, just to get to the cursor control on the nook, you have to turn on its color touch screen (which is normally off when not in use, to save battery power). This adds to the lag time.
* Screen contrast
You've seen Amazon's claims that the Kindle 3 e-ink has 50% better contrast. I can tell you, it makes a difference, particularly in low light conditions, when you have to strain a little to make out the not quite as dark characters on Kindle 2 and Nook. When lighting is not ideal, it's much easier and more pleasant to read on Kindle 3 and Kindle DX than on Nook or Kindle 2.
* Battery life
The nook's color LCD touch screen drains its battery quickly - I could never get more than 5 days out of a charge. We got at least 7 days or more on the Kindle 2, and supposedly the Kindle 3's battery lasts slightly longer between charges than Kindle 2.
* Weight
Nook weighs about 3 ounces more than the new Kindle, and you can really feel the difference. Without a case, Nook is still light enough to hold in one hand for long reading sessions without fatigue. But in a case, Nook is a heavy sucker and wears you out after a while. I found myself taking Nook out of its case when I was reading Girl Who Kicked the Hornets Nest. The new Kindle 3 is so light, even in a case, my wife and I read on our new kindles until quite last last night, each holding them in their lighted leather case with one hand (we are such an old married couple!).
Reasons some people might prefer the nook:
* In-store experience
If you need help with your nook, you can take it to any barnes and noble and get a real human to help. You can take your nook into the coffee shop section of your local B&N store and read any book for free for up to one hour per day. When you take your nook to B&N, some in-store special deals and the occasional free book pop up on your screen.
* User-replaceable battery
After a year or two of moderate use, the battery will start to lose its ability to hold a charge. Nook's battery is user-replaceable and relatively inexpensive. To replace Kindle's battery, you must ship your Kindle to Amazon. Amazon's customer service told me that they ship you back a DIFFERENT kindle (though the same model as yours) with a new battery inside. I really don't like this, at all.
* ePub and loaning e-books
Nook uses the ePub format, a widely used open format. Amazon uses a proprietary ebook format. Many libraries will "lend" ebooks in the ePub format, which works with nook but not kindle. Nook owners can "loan" ebooks they purchased to other nook owners for up to two weeks. You can't do this with kindle.
* Nook's color LCD touchscreen
This could be a pro or con, depending on your preferences. It makes nook hipper and less drab than kindle. Some people enjoy using the color LCD to view their library or navigate. I did, at first. But after two weeks of use, and comparisons with my wife's kindle, I found the dedicated buttons of the kindle easier and far quicker to use than the nook's color touchscreen. I also found the bright light from the color screen distracting when I was trying to read a book or newspaper (though when not in use, it shuts off after a minute or so to conserve battery).