As of right now, there are only 5 chapters, but it's still worth reading.
(Light spoilers)
Overall, there aren't any issues i can find with the manga's story, it's your classic "beauty and the beast" scenario you find with manhwa like Beauty And The Beast Girl.
There's a slight comedic sense to Miltia's antics, due to her being unfazed and even jealous of the duke's curse (which makes him infinitely create seafood using his body).
Although there is a bit of an issue with chapter 3 or 4, with the letter being disregarded, that's the only insance of a plot error i can find. It may not even be one, because of how few chapters there are in the manga (it may be addressed later on).
The art is great, there's a lot of detail to the Duke, as well as his little fishy friends. That level of detail remains consistant, and kinda cute.
For characters, the 3 main characters are appealing.
The duke isn't necessarily ugly, his design reminds me a lot of Davy Jones from the Pirates Of The Carribean movies, but with a bit of a goat muzzle going on. I love when characters are given weird shapes and designs, and he is a good example of that, with big fat octopus tentacles that look like a pair of horns, a mustache, and a flowing epaulettes. He even has a massive mane of barnacles, which is an interesting detail.
The female lead is somewhat cute, with short green hair and a small stature, although nothing to really write home about. Her head is a bit more round, and her eyes tend to give a more innocent look, which goes well with her unfazed and home-oriented character.
The third character (or characters?) Is the maid robot (although the voice isn't the robot, but a guy talking through it).
The designs are very cute, with a stubby design with big alien eyes, and the futuristic rabbit ear look that is often seen on cute robots, there isn't anything that can be seen as inherently bad about it. Although, it may not be the most convenient for cleaning, whcih is confusing since they're maids, i cant blame someone for wanting a robot that cute.
Overall, the manga gets an 8.5