Yuuna and the Haunted Hot Springs, while sensual and not the most focused in terms of writing, is surprisingly entertaining with a good amount of characterization, some epic moments, and decent storytelling overall. I do appreciate that some of the fan service is done in a creative fashion, not a mean-spirited fashion. The animation is vibrant, stunning, and something I could watch all day, but I think it does have too much filler to shoehorn in fan service, but it doesn't ruin the series overall and I still enjoyed it. In fact, I do rewatch some of the episodes because they are nice. It's just a shame they never finished all chapters, meaning we'll likely never get to see the more emotional parts and the manga's ending.