I have just bought my first Android E-reader/ tablet and I'm completely amazed by it and what it can do, plus the range of freely available books.
I've signed up to my local public library, which gives me access to download books - some are time limited (just like paper library books), others are permanent.
It may need charging up occasionally, unlike a paper book, but its 32Gb to 96Gb of storage allows thousands of books to be available on it.
I've been a bit of a luddite so far as E-readers have been concerned, I just didn't think the experience would be comparable to holding a paper book in your hand, since this one was delivered yesterday - I have certainly changed my mind. It is very usable and very convenient.
Getting back to the range of free books available...
Some of those available go back almost to the middle ages. I expected them to be just scanned images, but all seem to be proper digital texts. I'm guessing they must have used some very capable OCR software to convert these, along with a very patient proof reader.
Mightily impressed!