A few years ago there was doubt the digital book market would ever catch on, so in that regard the Kindle, love it or hate it, has probably forced the issue commercially, even though a number of ebook readers were out long before the Kindle.
Any of the brand names have something to offer, and all the book formats (mobi, epub, pdf, etc) still come down to text and images, and most of the ebooks are still based in html, or "internet" format. The real issue of ebook marketing and purchase is the DRM, or security of the book.
Amazon's Kindle and Barnes & Nobel Nook each use a copy-protection scheme for their retail books. With the Kindle, it's a secure Mobipocket format (amz) which limits reading the book to a device linked to your Amazon.com account, and only secure books bought through Amazon can be viewed. In other words you can't buy a book from Barnes & Nobel or Fictionwise and read it on your Kindle. Likewise, you can't buy a book from Amazon and view it on your Barnes & Nobel Nook.
The Barnes & Nobel Nook reader accepts secure pdb and epub formats.
Most readers will also read a few other book formats that are not copy protected.
Both the Kindle and the Nook use e-ink technology, which is a plus in that it drastically extends battery life and in normal light is actually less strain on the eyes than reading on a lighted screen. The downside is it's harder to read in subdued light, but if you think about it the same would be said for physical books.
As has been noted, the biggest selling point for these devices is the ability to browse and purchase books directly from the device. Even if you don't have internet in your home, you can connect to the devices respective online store via a 3G connection (cellular phone companies' data connection). This is provided free, you don't sign up for an account or pay additional fees. Remember you mut be in an area where this signal is available. A lot of areas around Wilkes county may not have that.
In addition to the Sony readers there are still many other book readers available. One of my recent finds is the Jetbook Lite, with a retail value of $149. It's often on sale for less, and in fact I found mine for $119 with free shipping.
To me the best feature about the Jetbook Lite is that it reads virtually every known ebook format, pdb, epub, mobi, prc, html, txt, pdf, fb2. It accepts secure (copy protected) eReader books (pdb) bought from Fictionwise, Barnes & Noble, eReader.com. All you do when loading the book is enter the name and credit card number used when the book was purchased. This is the default copy protection for the eReader (pdb) format. The latest firmware for the Jetbook Lite only requires the registration info be entered once, and then any other book bought with the same info is automatically registered.
The Jetbook Lite doesn't use e-ink, it uses a reflective LCD screen, that I actually prefer to the Nook. It's easier to read in subdued light, and the text seems a little sharper. As with the Kindle and Nook, there is no backlight so you do need a light source to read.
It uses 4 "AA" batteries, with a non-stop reading time of nearly 24 hours. If you use hi-capacity (2800 mH) batteries and only read for a couple hours a day, you'll probably see nearly twice that battery life. You can also use rechargeable batteries.
The screen size is slightly smaller than the Nook or Kindle, with a 5" diagonal vs their 6" diagonal viewing area.
It has an Auto Page turn setting, and you can rotate the screen 90 degrees. You can also zoom in on image-laden PDF files, something you can't do on the Nook, not sure about the Kindle.
It doesn't have wireless delivery, but remember it's nearly half the price of those that do. Books can be loaded into the internal memory (100 MB) via USB (a slow 1.1 version) or SD cards (up to 32 GB).
The original Jetbook is virtually the same except it has a built in Li-Ion battery and at this time doesn't support DRM (copy protected) books.
So my two cents worth is, if you're buying for someone who doesn't have internet, or travels a lot (retired couples), then absolutely a Kindle or Nook is a great choice. But if they have internet, know how to download and use SD cards, a Jetbook Lite or Sony might be a better option.
As a final note though, an advantage the Nook (and the Jetbook Lite) has over the Kindle is more buying choices, and the DRM books bought for the Nook can be downloaded and unlocked as many times as you want, they're not limited to only certain devices or a maximum number of downloads. This means that once you've bought the book, as long as you keep the registration info (name and CC #) you can enjoy that book virtually forever.
Peace, light, and Happy Reading.
