I liked the first half of the season, which made me laugh sometimes and has some laudable story morals, but by the end I was fairly bored. It's a children's show with two travelling protagonists who have episodic adventures. Nothing connects to anything else and there's no drama that really involves our heroes.
For what it's worth, it's based on a smartphone game.
Yuu (the Apathetic Boy) is a healer, like his father, which means he can pacify monsters. (I like this. It's better than killing them.) Unfortunately his father is also an adventurer who goes off on quests for months at a time. Yuu doesn't like that, has a negative view of healers and is frightened of monsters.
Merc (the Girl in a Bottle) is a water spirit in a moderately large jam jar. It's about the size of a beer mug. Merc can make her jar levitate and fly around, which is handy for reconnaissance and seeing over things, but otherwise she's pretty much useless and is just a tiny, cute girl who's made of water. She'll encourage you, though. She's nice.
They'll go on adventures together. What's mildly frustrating is that both have potential inner journeys, but neither gets taken to fruition. Yuu learns to chill out about monsters and his father, but we don't see him reunited with Dad and sorting stuff out. Meanwhile Merc (the title character of Merc Storia) has amnesia that is never explored or resolved. She's travelling in order to cure it. Doesn't happen. Apparently the original game also explains who she really is and how she came to be a water girl in a jar, but we don't learn that either.
Instead, the show's a bunch of random stories where Yuu and Merc are just passing through. These often involve themed magical countries, so there are cities of singing bird people, angels with wings and haloes, fairies, etc.
1. "The Apathetic Boy and the Girl in a Bottle" = setting up the show. I quite liked it
2. "The King of Dawn and the Imprisoned Bride" = a worryingly young mayor's daughter promises to do everything to make her arranged marriage a success! Yikes. No, just kidding, she runs away. "Do you have to be feminine?" It's exploring old-fashioned views of women and demonstrating how they're wrong, which is funny and satisfying.
3-4. "The Tomboy Fairy and the Spring-Eating Dragon" = a fairy princess (and overweening brat) runs away because she doesn't like her butler's history lessons. She manages to get taken for a dragonslayer, which is funny, because she pulled a sword from a stone. Because she's an airhead. She learns, though. This story's good too. There's even a casting gag in Queen Floreida and her daughter Princess Sarodia being played by real mother-and-daughter Kikuko and Honoka Inoue.
5. "The Red Star of Evil and the Brilliant Ruler of Superior Flame" = again, I quite liked this one. Another princess (there will be many in this show) has been cursed. I liked the monster chasing her because she'd trodden on its tail, which hurt.
6-7. "The Lord with You in Dreams and the Town of Oblivion" = the fantastical town of Alloween (with a Jack Skellington-like figure) is also the country of the dead... but it's also just another country you can drive into by car. This is where the show started losing me. I like how mental it is, but the ending's pretty opaque. The ghosts were all illusions created by the monster or something.
8-9. "The King of the Song Altar and the Diva in a Cage" = I disliked this one. It's set in a city of bird people where your love confession is judged by its quality as a song. Real birds often do this, admittedly, but it still makes for a thoroughly unlikeable opening as the stuck-up Serena gives a suitor the coldest of brush-offs. We later learn that Serena's effectively a bird in a cage and we're supposed to feel for her predicament, but unfortunately I didn't care about her losing her ability to sing. She never warms up. She's cold from start to finish, worrying about what people will think of her. Personally, I was cheering for the voice-stealing crystal parrot, which made some good points and was promising to return the voice once it had been freed.
10-11. "The Angel Who Couldn`t Fly and the Holy Wings of Ten Thousand Prayers" = I didn't dislike this one, but I didn't feel engaged either. It's set in Heaven, which again bizarrely is a country you can visit. You've got to be able to fly, mind you. Everyone there has wings and they regard "groundlings" as walking sacks of sin... but that just makes it all the more awkward for the few who aren't "everyone". There's a girl who's revered as the holiest of angels, because she's got wings so huge that they're useless. She can't lift them. Other characters have tiny wings, or else none at all. Yuu meets a wingless boy, but frankly I didn't find them that likeable together. There's nothing wrong with them and there are indeed lots of boys like that, but I wasn't interested.
This two-parter also has a mildly puzzling relationship with its theism. Everyone's devoutly religious and talks about God all the time, which is unsurprising for a race of angels in a city floating in the sky, but... "I wanted to test whether or not God is real."
12. "The Healer and the Friend in a Bottle" = zzz, nothing.
Could this show tell you what it's about? Probably not. I don't think it's aiming for anything like that. It's not really going anywhere with Yuu and Merc. All the stories are standalones. It's a pleasant, inconsequential anime that's going for a younger audience and unfortunately puts all its best material in the first half. I can't imagine anyone hating it, but it didn't leave much impression.