It was a beautiful story although it only lasted for three episodes. Keep in mind that there's a full length series coming this October. I've never read the manga and I don't intend to read until the I've finished watching the upcoming anime series. So, in this review, I'll only be talking about what I think only from watching the OVA.
The story was beautiful. If you haven't read the manga, you'll be kinda confused at first but not that much. As far as I see, the OVA mainly focus on Chise's backstory. And I have to say, it was very good. From the first episode, it might seem like it's very slow paced but the main story kicks in starting from the second episode. And the pacing and the story matches very well. And at the of the 3rd episode, it might make some people teary.
There's nothing really I can say about it except it was amazing. The characters look good and sceneries are breath taking. But I can't help but feel that they could have done a little better considering this was made by the same studio which took part in production of Attack on Titan anime.
The sound tracks did't stood out that much but I have to say, it matches the story and setting very well. And he sound track did make the anime more beautiful.
The characters are pretty awesome. You won't see any of the character archetypes that you often see in other animes. But each characters were charming in their own way.
What can I really say apart from that it was really awesome. I waited for 1 and a half years for these 3 episodes and I'd say it was worth the wait. It was everything I hoped it to be and even more.
Overall, this is a kind of anime that you won't really find that often. And it's still just an OVA and there'll be a full length anime series coming October. It might take the anime fandom by a storm or it might become a hidden Ruby among the anime fandom. These 3 episodes were conducted really well and makes me hyped for the upcoming series.