The wife has a Kindle 1st gen, and I'd been eyeing the Kindle DX for 6 months before the iPad was announced and just couldn't bring myself to push that buy button. The iPad overcame my last objections to the typical eReader - no color and the fact that I'd still require a book light for my reading habits better than 70% of the time.
There's no question here for me. The iPad has dealt a death blow to every eReader priced at $250 or above.
The touch screen... even just for turning pages blows away the Kindle we have. The iBook app even has the option to turn the page forward with a tap on either side of the screen. You'll see the advantage when you start using it. With options for white, black or sepia screen, along with brightness adjustment, font size and even a few selections of fonts.
Color - did I mention that? The National Geographic looks fantastic. So do Marvel comics, Archie comics and several more comics already working on optimizing their iPhone apps for the iPad and surely more will follow or be left behind. Zinio has around 150 mags available already, among them: MacWorld, Sporting News, PC Magazine, Smithsonian, US News & World Report, BusinessWeek, Rolling Stone, Sail, Bike, Skiing, Billboard, Spin, Motor Trend, Cycle World, Road & Track, MotoCross, Field & Stream, Outside, Outdoor Life, Popular Photography, Modern Painters, Layers, and for the women out there... Elle, O, Bazaar, Cosmo, Redbook, MStewart Living....
Thus far the glossy display has not been an issue for my personal use (and I am one of those that hate them) since I do most of my reading at night or in dimly lit rooms. It has been when I pull it out to show it to folks though. Finger prints are a problem, especially for those with oily skin, but typically not noticed until you turn it off. I do have an anti-glare, oil resistant screen protector on the way (hoping it's the same I have on my iPhone).
Amazon already has the Kindle reader updated for the iPad and the books look great. B&N and eReader.com should have updated apps out soon.
It's in color, brilliant color in fact, did I mention that? This is the eReader I had been waiting for. And no book light. Those things have always been the bane of my existence when trying to read in bed at night. As an eReader alone, I have no problem recommending the iPad as my instrument of choice.
There is one con - it's heavy. About the same as the last Harry Potter book. For those that buy hard back books, not a problem... you already know how to deal with the weight. For those that have been purchasing nothing but paperbacks for years, well, you're not going to hold the iPad up in the air with one hand for hours at a time while you're engrossed in a novel. Not even an hour. I'd surmise not even a half hour for most of you.
You'll be setting it in your your lap while sitting, or on your belly while lying down. Laying on your side with one arm under the pillow, holding it with the other hand and turning the page... that's not a problem.