The Kindle is my first e-ink reader. I own an iPad, an iPhone, and have owned a Windows-based phone in the past that I used as an ereader.
My overall impression of the device is good.
The good: I'd honestly rather read linear (read from page one to the end, one page at a time) fiction from it than a book, because I can't always get comfortable with a book. Hardcovers are sometimes a bit heavy, and paperbacks don't always lie open easily. The Kindle is incredibly light and thin. I can hold it in one hand easily. The page turn buttons are conveniently located. Page-turns aren't instant, but they're probably quicker than turning a physical page in a printed book (there are just a lot more page-turns unless you choose a small font). The contrast is better than other ereaders I've seen. There is zero eye strain in good light. My eyesight isn't the greatest and I like being able to increase the font size and read without glasses. I love being able to browse the Kindle store and read samples before deciding to purchase. The "experimental" browser is surprisingly usable, but isn't great. It is useful for browsing wikipedia and blogs. The biggest drawback to the browser is the awkward pointer navigation, using the 5-way pad. It syncs your furthest read page over the internet so you can pick up where you left off using your iPhone or iPad.
The so-so: The kindle store could use more categories and sorting options. You can't sort by "top rated," and there is no category for "alternate histories," for example. Finding a very-specific type of fiction relies on keyword searches, which don't do a great job. The wifi sometimes doesn't connect before it times-out. You rarely need the wifi, but it is annoying if you change a setting, answer "OK" to the prompt to connect, and the thing tells you it failed to connect two seconds later (the exact moment it indicates that it did finally connect, then you need to go back to update the setting again). Most settings don't require a connection, but it is a minor annoyance. Most of your time will be spent reading, and of course your books are stored on the device and a connection is not required. Part of me wishes I'd bought the 3G model, because the browser is good enough that having lifetime free 3G wireless would be worth the extra money. Magazines don't look very good and are not very easy to navigate. There is minor glare in some lighting conditions, mostly when a lamp is positioned behind the reader's head.
The bad: The contrast is fair to poor in dim light. It is much easier to read a printed page in dim light. In good light, contrast is on par with a pulp paperback. In dim light it feels almost like reading from an old Palm Pilot (resolution is better than an old Palm, but contrast is bad in dim light). The screen is small enough that the frequency of page turns is pretty high. Even in good light, the light gray background is less pleasant than the eggshell background of a printed page. You must tell it to sync before you switch it off, if you expect the feature allowing you to pick up where you left off using other devices to work correctly. The copy protection prevents you from using the files on anything other than Kindle software or devices.
Vs iPad: IPad is a lot better for magazines, reference materials, and illustrated materials. Kindle is worlds better for reading novels. IPad is pretty heavy, making it more difficult to hold in your hand or carry with you everywhere. Kindle is much more portable and easier to hold. IPad has some amazing children's books and magazines, which take advantage of its multimedia features. IPad is unreadable in sunlight and glare is bad in bright light. Kindle is as good as a printed page in bright light. Ipad serves as a creative tool, a computing tool, a gaming tool, and a communication tool. Kindle is only a novel machine. I don't regret buying either one of them. An iPad won't replace books, but a Kindle can, if the book is text-only.
I highly recommend this device at its new low price if you are a frequent reader of novels. I love my kindle. Just don't expect it to be more than it is. Leave the magazines and such to the tablet computers.