No opinion on what's the Mangaka's deal right now, but I would indeed say that both the film version and the novel version are better than this one. They provide more content while this "manga adaptation" barely does any worthwhile innovation. I mean unless you're a die hard manga fan who doesn't like watching anime then you're better watching the film or the novel anyway.
(And did the artist say anything regarding their attitude towards this stuff at the moment? I don't know much about the industry, but I thought all the artist for the manga adaptation had to do is to copypaste the story in Manga format, dice it into consumable parts, paired with extra ideas where the film couldn't do but still enhances the main idea's performance.)
Also this manga just experienced quite possibly the most radical drama-related rating drop in Yuri history of the entire site. a 0.8 score drop in a mere few days and 0.1 drop in only a few hours.