Story: it's not riveting, but it's not weak either. Honestly, the plot isn't the star of the show, and that's fine. The character interactions and aesthetics make up for it.
Art: Not only is the art style gorgeous, but just. Plant gore. The flowers are gorgeous, and how they're illustrated growing out of bodies rules. It's fantastic to look at.
Character: While you don't necessarily finish the story with an in-depth knowledge of who they are as people, the two leads have a very loving and refreshing dynamic that takes center stage in the story. Most of the manga is just them interacting, and it's a nice relationship to read about. They're both likable characters.
Enjoyment: It's hard for me to judge this objectively because I'm so into plant gore (and loving relationships). Since it's rare for me to find a manga that hits my tastes this well, my enjoyment was magnified.
However, I think it likely does well just by BL terms. The plant stuff isn't actually very gorey (I'd personally like to see more visceral depictions), so I don't think it would be off-putting to those who have no interest in horror imagery & just want to view it as pretty. And outside of the flowers, it's just a sweet love story.
