It's my understanding that you can relatively easily transfer Amazon ebooks to nook or kobo readers, so is this really a big deal?
Personally I'm just planning to buy, but think I prefer the slightly less locked-down nature of the kobo over the nook, and (more so) kindle.
It's fairly easy, but can't really be discussed in detail because it's not fully legal. Basically if you buy from a store not supported on your device, you have to download to your PC, convert, and then sideload to your reader. It's not hard, but a little cumbersome compared to purchasing directly from your device and never having to plug into a PC period. That's what I'm doing on my Kindle now and I much prefer it over all the sideloading I did on the Nook, as I rarely bought stuff from the Nook store. Amazon has been the cheapest for the books I've been interested anyway so it made sense.
What do you mean locked down? If anything the Kobo reader is the most complicated because you'll have to convert both Barnes & Noble books AND Amazon books which are the major players right now.
Kobo has its own store, but those are still DRM protected. You would then have to convert all ebooks from B&N AND Amazon to use them. With a Kindle, you'll only have to convert B&N books (and I guess Kobo books if for some reason you used them still). With a Nook, you'll have to convert Amazon and Kobo books. All three have the same problem in that they don't read other stores' books natively. But (at least in my case) Amazon's store is the better buy and I also have Amazon Prime already.
Also, Kobo doesn't have a version with a built in light. That's a huge dealbreaker for me personally because I read in bed and don't have a lamp.
I can understand this viewpoint, but what if you want to look at full color pdf's? I can't imagine an e-ink device is good for that.
Completely different markets for completely different types of reading. Personally, I find any LCD reader at this point so awkward for general book reading that I'd rather have a separate device for novels and a tablet for color stuff (magazines, comics, whatever you want). They're heavy, have comparitively poor battery life, and even at the dimmest brightness setting have a rather high brightness that is kind of harsh in a dark room.