I believe that, in the end, the good bits outnumber the bad ones, which is why I gave this series an 8 out of 10 overall. The essence of the series is good and most things were taken care of pretty well, but some others seemed to be put there carelessly or were just neglected. I'll try to sort my feelings about Moonlight Chicken as best as I can.

Starting from the plot and the overall narration: I believe it's good enough, but not really as good as it could be. The story itself is pretty simple (no surprises there since it's an obvious slice-of-life), there are a couple of major surprises but nothing huge. Something that I really liked about it was the cinematography, along with some specific dialogues and symbolisms sprinkled in: it felt like being fully immersed in the life of the characters and the metaphors and parallels made for a very satisfying watch during the most important scenes. What I didn't like was how the show seemed to cling onto the "realistic" side of it all way too much for my taste, to the point that a good chunk of the events are very anticlimactic - even when they were really important, I ended up not feeling much about them. The pacing felt too slow at times, and I also had lots of trouble understanding how much time went by between the main events: in certain instances it feels like it's only been a day or two, then it's suddenly revealed that it's been weeks or months.
There are multiple interesting themes in the story as well: moving on from grief or a past relationship, learning to be responsible for the people around, learning to let other people go and make their own choices for their life, and so on. These themes found their place in multiple characters and situations, but not all of them were explored as in depth as they could have. Since the pacing already felt too slow to me, I believe that putting some of these ideas aside might have helped to let the others shine more.
I wasn't able to enjoy the story as much as I wanted because it felt incredibly bitter, with money issues and lack of understanding among the characters looming over all the episodes like a huge black cloud. But that's just my preference and I'm not considering it an actual flaw.

As for the characters... well. Like others have already said, Earth was not the right actor to interpret Jim. Earth is about my age, so I kept feeling very weirded out when I saw him being called old and being treated like a middle-aged man at all times. I feel especially bad about it because Earth is a favorite Thai actor of mine, and also the main reason why I decided to watch this series in the first place, but he just isn't the right fit for this role. I believe that the other actors were a good choice, but since Jim is the main character and basically everyone interacts with him at some point, he made a lot of interactions feel off.
The characterization was pretty good for all the characters, support roles included. I liked the fact that no character was entirely perfect, and rather than making villains and heroes out of nowhere, there was just a group of people doing their best with their life.
As a couple, unfortunately Jim and Wen weren't interesting enough to me. Aside from Earth trying to interpret someone 10 years older than he is, I just didn't feel any chemistry between them. I don't believe it's the actors' fault since they had incredible chemistry in other series I watched with them as the main characters; it's probably because of a combination of overall mood and pacing to me. I saw some sparks on the very first episode, but then their individual circumstances made each of their appearances feel oddly gloomy and uncomfortable. I felt like Wen wanted to stick around for no real reason other than, well, the plot.
Li Ming and Heart were absolute show stealers. The acting of Gemini and Fourth is already amazing at their young age, and Gemini in particular did amazing portraying a deaf character. Their chemistry was incredible to see even in their smallest moments together, and the development of their relationship was steady and well-paced. Their story was also easily the most lighthearted of all, so I unconsciously started to look forward to their moments instead of focusing on the bitter and gloomy main plot.

In the end, I can say that it's a good series and that it should be watched at least once, but at the same time I can't recommend it. I don't even see myself picking this up again in the future, if not to watch Li Ming and Heart falling in love one more time. It can be good if you want to watch a more serious Thai series and take a break from goofy comedies with lots of sound effects, but that's it.