The book ended.
Several story questions remained unanswered. There is a difference between holding a paperback in your sweaty palm and holding an ebook therein. For one thing, you're holding a Kindle, an iPad, or something, but the big thing is that a Kindle feels the same when the book is on page one as it does on page three hundred.
In my decades of reading paperbacks, I could always feel the number of pages on the right side of the spine. When they got thin that gave me tactile feedback that this novel is almost over.
I recall reading Cryptonomicon and thinking, "wow, there's a lot of dangling threads of this novel and there's not that much paper under my thumb." And that novel tied most of them up, but the last chapters felt like a train wreck.
In an ebook, a novel can end without warning. Well, actually, there is a warning, but you have to look for it. There's a progress bar that will tell you if you have the sense to look at it. It's less automatic than a thumb on the book's spine.
My friend clearly intended to write more later. And I had to wait for a sequel future installment. That never came...
Earlier this week I had a similar experience when I read Sliding Void by Stephen Hunt. To be fair, he advertises the work as a novella, and he gives it away free. So, I have no basis to complain. And unlike my friend who hasn't published another installment, both the 2nd and 3rd novellas in Mr. Hunt's series are currently available.
So, how many stars for Stephen Hunt's Sliding Void? I liked it, but I'm giving him an "incomplete" I'll let you know when I finish the 2nd and 3rd installments.