[Ruskie_it]

Originally Posted by eschwartz

When you try to turn a page that doesn't exist, it is not completely unintuitive that it doesn't turn the page... Turning the last page in a pbook doesn't close the book, it merely leaves me scratching futilely at the inner side of the back cover flap.

It is of course intuitive to press the home button when you are done an ebook, much analogous to closing a pbook.

Exactly this. I can't do what you ask me to, I don't do anything.
Not "I do something completely different which may, or may not be what you really wanted me to do".
One is the way "Unix" behaves, the latter is Windows/Mac style (I stick to this analogy because I have read you enough to know you will get the analogy).
It's not all the way bad that it gets back to home, as we can clearly see there is a lot of people who actually prefer it that way, I am not at all saying that nobody can like that, let's be clear. I'm just saying that this leads other people to be unsatisfied, because you have decided "it is best for all" to act that way. Which is, imo, untrue.

Perhaps I am just used to the Kindle's way of doing it, but I cannot see why turning the last page should close the book.

I rarely turn the last page meaning to leave the book, generally it is because I don't realize there are no more pages. With a pbook is much easier to spot this.

Again, exactly.
This is it: ebook readers (I mean softwares, not devices) have two input buttons to this regard, which works consistently in all the application on every device for every page but the last:
a) Move one page forward (this is the swipe left, or right button for non touch devices)
b) Close the book and put it on the shelf (this is the home button)

If you WANT to close the book, you press the home button. What happens here is that in case this is the last page, right button turns to be the home button. That one might like this best is possible. But it cannot be asserted that this is consistent.
You might or might not notice you are in the last page of your book. If you do, pressing home or swiping right is exactly the same. The fact that someone prefers swiping left does not, and can not imply this is better: it's a gesture we are talking about, doing one or another is the same, and certainly you can't say "Swiping left is faster because I am already doing this": it's not a "turn pages fast" contest.
If you do not notice you are at the last page, instead, problems arise. But while "doing nothing" does not harm you: you still have options to do everything: you want to close the book? Home. You want to go re-reading last pages (sometimes I do)? Swipe back.
"Closing the book" might harm you: you wanted to close the book, fine, you already did. But if you wanted to re-read last pages you have to re-open the book, you are at first page so use the keys to open up navigation, go to last page then swipe back... way more complicate.
Sure, this is not rocket science and the world does not rely on us being able to re-read that pages easily, no. I am just talking about "usability", and there are quite precise rules about that.

Of course, the Kindle is not ideal in this regard either -- it opens a popup asking you to rate the book, even if it is a sideloaded PDOC.

Oh no, Kindle is not better at all, from the usability point of view: simply replace "close the book" with "display that annoying popup".
On the contrary: I suspect there are way more people that at the end of the book want to go back to the shelf, rather than people that at the end want to let the world know how they rate that book (and only if it is not a sideloaded one). So we might argue Kindle does even worse. On the other hand, it's easier to "recover" from the unwanted popup: go back where you are is just a matter of tapping the X.