IF you happen to also be thinking to get a netbook or tablet or anything like that, I would recommend getting an iPad instead of these stand-alone e-readers.
I was also in the same boat as you a month ago, and I looked at all the options, and I thought with an iPad I can also do my emails, browse the web, listen to music, and do a whole of other things with the apps. Yes, unfortunately it costs about 3x more, BUT with an iPad, you can download all the e-reading apps from Amazon, B&N, Kobo, and of course Apple's own iBooks. I love having the option to pick and choose who I want to buy my ebooks from. Personally I think even though it's more expensive, it's a better investment in the long run.
Kobo's app is pretty decent too. And all these merchants may be competing right now to give you discounts/promotions on ebooks. Each app has its own advantages/disadvantages. iBooks has seamless page turns, Nook and Kobo has the night reading feature that I love to use. They basically switched the background from white to black, and vice versa for the text, so you can read in the dark with very little glare from the screen. With kindle or nook, you can't read in the dark at all... From all the iPad e-reader apps I've downloaded, I'm most disappointed with Amazon's. I think they deliberately spend less time updating their iPad app so that people will buy the kindle hardware instead.
The graphics are also more aesthetically pleasing to the eyes on iPad (if you care about that at all). And if you have ebooks in EPUB format, you can basically read them from iBooks (by adding the books to your iTunes library). I still don't know how to add these epub books to the B&N e-reader app or kobo yet. They (and the Amazon app) basically connect to your store's account and access the books that you have bought from their stores online. So you can't read anything that you've bought (or obtained) from other stores.
I'm also a bit of a reluctant convert from regular books to ebooks. I still purchase regular books, but I can't deny that the ebooks give me joy because I can highlight certain things, make notations and bookmarks and can easily refer to them later on. Or I can search the entire book for a phrase with just a click of a button. Right now I'm just worried about how to back them up to make sure I don't lose them... I think it's easier to lose a digital file than a physical book...