Imma be brutally honest.
The concept was interesting but they were either crammed or not discussed enough. The animation seemed lazy or maybe the team had time issues so that can't be helped. I'm not sure if it's the voice acting or the mouth and the little movements animations that make the scenes look basic and lacking in emotion.
The flashbacks weren't smooth. It's like, why would I care of her past when I still don't know who she currently is? There wasn't any clear reason as to why the flashbacks were there except for building it up for the final episode. I would have preferred they focused the 1st season on the characters and many some subtle important build ups. That way the characters won't be dull and we could actually get attached to them. It's the twins that are bearable. The episodes would also not feel so crammed if they just gave some space for us to like the characters, know what they are dealing with, their human imperfections, and habits.
The mood was dull. Even if the series is horror, supernatural, or mystery, there were some unfunny funny scenes. It seems like Trese's not the type to smile and although they did use the other characters to add humor, they weren't very effective. The decent artstyle they used could've been more expressive and maybe goofy for those scene to work. The sad scenes as well weren't powerful.
Overall, the best I can describe the series is that it feels like I'm watching a youtuber's gameplay of a roleplaying game like Fire Emblem (but I bet I would enjoy watching a fire emblem gameplay more than Trese). Other people who say that Trese's perfect and super amazing or something may be biased just because it's a Filipino-focused show. The story was really interesting but the other stuff makes me want to not finish the series. I don't have anything to expect, the suspense they give off is very little, it's underwhelming. The charisma of the main protagonist was difficult to take notice.
I mark this as mediocre, but it's on par with some popular shows in the Philippines.