I know a lot of writers get really worked up about reviews and reviewers, stressing over the quantity and ratings level as if they were a factor in the welfare of the universe. I've seen some writers go ballistic over a single poor rating, or get in flame wars with reviewers or other writers about ratings. Myself, I follow Eric Flint's philosophy for the most part. No writer is going to please every reader with every work. It just isn't going to happen. So as long as I'm telling the best story I can tell, and as long as most readers seem to like it, I don't sweat it. (Of course, if a story gets uniformly poor ratings, that tells me I probably didn't tell a good story. That's my fault, not the readers'.)
But I will confess that there's one thing I find a bit odd about reviews and reviewers that will occasionally kind of ruffle my feathers. One of the comments I frequently see in readers' reviews of books goes something like this:
"I really liked the book, but I've read too many of the stories elsewhere, so I'm only going to give it three (or two or one) stars."
People who say things like that really don't seem to understand how story publishing works. If you're in that category, here's how the traditional model flows:
1. First cycle: Stories first get published in venues that promote and accept new short fiction. Those are usually either magazines or original work anthologies. Until a few years ago, there were enough magazines in the market that a good writer could generate respectable cash flow from writing stories, because if one editor didn't take a story, the next editor might. (This is the reality behind Heinlein's Fifth Rule of Writing: "You must keep [the work] on the market until sold.") Traditional magazines have been dying out as story venues, but on-line e-magazines keep popping up, and we may well see them fill that writerly ecological niche.
2. Second cycle: Historically, story anthologies would occur to either collect the "best" work of a time or place, or to present work that supports a particular theme. So, you would find "Best SF of 1969", or "Best of Magazine of Fantasy and Science Fiction 1963", or works like the series of anthologies called "There Will Be War". Even today, you will find a lot of these types of anthologies. Until relatively recently, these were the rule and anthologies of original fiction were the exception.
3. Third cycle: Once a writer has a sufficient quantity of stories that have been published in various venues, then the writer (or sometimes an agent or publisher) will begin grouping them in collections and publishing them as such. Sometimes the collections are just sort of ad-hoc collections of stories by that author; sometimes they are thematic collections where the stories gathered together all relate to one another in one way or another.
Here's what a lot of modern readers don't seem to get: There is nothing new or unusual about this practice. As long as such a book is not being marketed as containing all new or all previously unpublished material, it is not deceptive or underhanded to do this. This has been part of the short story publishing model for generations. And really, do you expect every single story anthology or collection to always be totally original work? Every time?
This actually does a service for readers. If you really like a series of stories that were published in a variety of venues and issues/editions, having them all pulled together into a single volume is a great thing for you when you want to reread the series. Instead of having to have maybe fifteen or twenty different magazines or anthologies stacked around or loaded on your Kindle—or even worse, having to hunt them down to acquire them—and having to figure out once again what order you have to read them in, you just pick up the collection volume or open up the collection e-book and there they are, nicely together, formatted the same for consistent reading, and in the right order without your having to do anything. Personally, speaking as a reader, I love it when authors do this.
So be fair....it's okay to comment in a review on the fact that a book contains some (or a lot of) previously published stories, but unless the book is being misleadingly presented as being all new stories, it really isn't fair to lower the rating. If you thought it was four star good before you realized it wasn't all new material, it should still get a four star rating as long as it's not being misrepresented.