I bought this book because I wanted to read WEIR OF HERMISTON, which is hard to find these days.
WEIR OF HERMISTON is a sort of gothic romance novel, it is the book that Stevenson was working on when he died, and is considered by some to be one of "the great unfinished novels." I did enjoy reading it, but the story was just getting good when Stevenson finally succumbed to his lifelong health problems and died. WEIR OF HERMISTON is reminiscent of Thomas Hardy's work, and it is a pity that Stevenson never got to finish it.
Is it great literature? I wouldn't say so, but rough drafts rarely are. I recommend against reading Stevenson's friends descriptions of the ending he had planned. Such testaments are inevitably trite, spoiling, and cannot be trusted anyway. Authors often change their minds about plot points, endings -- pretty much everything.
I give the book five stars, because of course DR. JEKYLL AND MR. HYDE is a brilliant literary work, and because I'm a Robert Louis Stevenson fan.