Overall this is an ok series with a good story progression, good characters and visuals and an okey-ish ending.
But precisely those same points are the problem for me as it ends up being a bit superficial in all aspects. There is a good story progression but there are plotholes and unexplicable decisions, especially towards the end, that could have easily been tackled considering I found the show slow at some points.

Characters are good but I didn't feel like I got to see very deep into them, probably only Soramame we get to see more into her psyche than anyone else. The most frustrating are the side characters, there isn't any progression for any of them, especially I was waiting they would do something with the landlady Kyoko, she was such an interesting character but she's just support role, literally.

Both of their careers are pretty unrealistic, especially hers and we're not told at any point that she used to draw or was into fashion growing up, it's very out of the blue, and then she happens to have connections in the industry, what are the chances... I can let it pass, it's ok. What it's not so ok is that there is a build up when it comes to the mother and such a drama when her ideas are stolen but then when we get to the resolution and she gets what she technically wanted then we get a time jump and all of a sudden she's back and out of it all and it's not really even well explained exactly why she seems so burnt out, her replies are very ambiguous.. Am I to assume it's only because she's not with Oto? Why did she go in the first place then? and why in those three years she didn't think in telling him how she felt at least to move on? (considering she thought he was with Seira). Instead of rushing it, it would have been better to end the show with them telling each other before she went, end it there.

The time jump adds absolutely nothing and only creates more questions and more frustration. I find the time jumps in modern setting dramas to separate lovers completely ridiculous (unless it had a good reasoning, and I still haven't seen one). You want to use that plot device? set your story pre-internet era because otherwise it's just unrealistic (and still, phones anyone???). Who in their right mind loving someone would not speak with them for 3 years at all and hope they're still single and in love with them, especially after a very generic letter and an earphone as a token of love. I get it, it's supposed to be romantic and it would be if their separation had been a few weeks/months long, but three years?
Then what's going on with Soramame in the end, I feel at that point I don't even know if she's still into him or not, she receives the invitation and it's a "yes but no", all that part of the story is like seeing a toddler going to school in the morning half crying, I'm not sure if I have to feel joyful for her or suffer with her because she's doing something she doesn't want. It's so vague and anticlimactic in my opinion.
I don't even know where to start with Seira, she was a mess in the beginning and I'm still not sure of what her situation was, because I don't even know how many layers of lies there are there and her character, like any other side one, is kept mostly superficial. Either way, she started as a bad person and ended as a bad person, there is nothing there that tells me she has grown to be a better one. I mean, she took three years to tell that to Soramame... but I don't even know if I can blame her considering Oto didn't contact Soramame either to tell her what she thought was not true either. They both basically left Soramame to believe what she assumed for three years (and obviously Soramame is also in the wrong for making assumptions without asking). Seira doesn't suffer at all the consequences for her actions, not the first time and not at the end.

The love progression in this one is the frustrating type, so if you're not into very slow burn love stories where characters play very dumb till the end then this might not be for you.
I liked the visuals and settings of the story and I enjoyed the main characters banter and the dynamics of them with the landlady. I could understand that plot twist with Soramame's career towards the end if there was a second season, I can't find info on that so I'm going to assume there isn't one and so it's a bit annoying to see the progression of her career and then she stops but there is no hint on what she really wants to do next, more considering we're only told at the end once they're together that she's just like in a hiatus career wise. There are many things they could have done to bring her back to Japan instead of that out of the blue burnt-out when she's only been in the profession for 3 years. For example, in the lines of what she was saying, it would have been a lot more satisfactory that she had said high fashion is not for her and she's planning to create a small brand that provides to the local community, instead we got vagueness and not enough time to dwell in that vagueness, the motives, the reasons and the progression out of it.

Music was ok, sometimes it got a bit repetitive for me though.

Overall it's an ok watch so I would recommend to those that want something to watch, but if you have something more interesting in your list watch that first. Avoid if you don't like slow burn romance, it can certainly be quite frustrating in this one at times.