I'm a huge sucker for romance anime, and this one actually has it all. It's got an interesting hook and characters with actual personalities. The main plot is a romance between an aristocratic heir who was cursed by a witch as a child to kill all he touches (hence the "Duke of Death"), and his maid, Alice.
The pace of the romance between the Duke and Alice feels incredibly natural, and the chemistry between the two is clear with an actual backstory to it, instead of it being 'just because.' The dynamic between the two of them balances out quite nicely. Even though Alice technically works for the Duke, and on paper he has authority over her, she has all of the power over him emotionally. Their personalities compliment this dynamic as well: the Duke is timid and easily flustered, while Alice is playful, teasing, and is shown multiple times to be quite perceptive and cunning. But the characters don't feel static- there is plenty of character progression for both of them.
Rather than detract from the primary romance like so many other side characters do in different series, the side characters in this series actually serve to further the romance by introducing conflict from their respective worlds, and thus giving reasons for the Duke and Alice to improve and their romance to grow. There are really two categories of side characters: the witches (notably Zane and Cuff, who serve as a side romance between the two of them), and the Duke's family (Rob the butler, as well as the Duke's sister, brother, and mother). To elaborate, Zane and Cuff serve as an introduction to the world of witches, and by extension, the hunt to figure out a way to break the Duke's curse. The Duke's aristocratic family, on the other hand, naturally sees the Duke's affection for Alice to be taboo, which serves as a catalyst for him to grow independently as a character. In addition, these side characters also have quite enjoyable personalities!
Overall, the romance is incredibly well written and paced. Would probably be between a 9 and 10 if it wasn't 3D animated. However, what is actually drawn in 2D is beautiful, and the mostly classical-adjacent music is lovely. If you love romance anime, don't miss out on this one.