I have had (still have, but no longer use) a Nook model 1 and am now using the Nook tablet. Herself has the smaller Nook model 2. We both use them for free epub files, both from the library and the Gutenberg Project. The tablet is small - the same size as the original Nook, just about - but is web-capable so one can do email, surf, watch Netflix movies, etc. It can handle .pdf files, but I haven't used it for that, so I can't properly comment. As previously noted, it has no hard drive, so one cannot put programs on it for such things as word processing. The tablet does have a backlit screen; I do a lot of reading and haven't noticed any problems with it - I dialed the brightness down and selected the black on light grey screen option.

Once you have the Adobe Digital Editions loaded, it takes just about no time to transfer a book from a library to the Nook. The only issue is that you must have a real computer in between; you cannot transfer directly from the internet to the Nook. The same is true of Gutenberg books - I have no idea if one can load directly onto a Kindle. My library's web site says that it does not support the Kindle - that is, one cannot check out their ebooks and transfer them to a Kindle.