Brilliant Books in Traverse City, Michigan, posted a blog on its website warning customers that the story is "not a sequel or a prequel to To Kill a Mockingbird. Neither is it a new book."
While Harper Lee won the Pulitzer Prize for her 1960 novel about race in the South, this next book falls short, according to the bookstore.
"It is a first draft that was originally, and rightfully, rejected," the blog read.
The store urged readers to view the book as a source of academic insight, not a fully realized novel.
Store owner Peter Makin told PEOPLE that he made the decision to refund customers when a woman came into the store to pick up the book she'd preordered on July 14 (its release date) and was so disappointed by reviews and early chatter that she wasn't even sure if she still wanted to read it.
"I had done wrong by her," he said. "As a professional bookseller I have a duty. If you come into my store and you tell me you don't like scary books and I give you a Stephen King book, and you have nightmares, that's on me. I owe you something on that. I gave you my professional opinion and it was wrong."
Makin believes it's important for the bookstore to stand by its recommendations.
"We are not offering refunds based on the quality of book or the content; it's because of the marketing of the book," Makin clarified. "It's not like people can read the book and be like, 'I didn't like it,' and bring it back."
The normal bookstore return policy allows customers to exchange a book, as long as it's in great condition, within 30 days. Usually there are no refunds; this time Makin felt he had to make an exception.
He says he felt partly to blame, having encouraged customers to buy the book in his weekly newsletters. As a result, he chose not to host any midnight book parties or other hoopla related to the book's release.
Go Set a Watchman is a follow-up to Lee's famed To Kill a Mockingbird. The new book centers on Scout, now called Jean Louise, as she returns home to Maycomb, Alabama, from New York City to visit her ailing father, Atticus Finch.
The book caused consternation among some fans because – spoiler alert – in Go Set a Watchman Jem Finch, Scout's devoted older brother, is dead. There was also a real struggle among readers who loved the morally upright Atticus in Lee's first book and couldn't reconcile him with the bigoted version in the new book.
So far, only a handful of copies of Watchman have been returned to Brilliant Books. "I think it's still our best seller this week," he said. "It was our best seller last week."
And as for his personal thoughts on the author: He can't say; he hasn't read either book.
I'm English and so whereas to To Kill a Mockingbird is standard reading in American schools, it is not part of the British culture," he said. "We get to read Shakespeare."