THE STORY:
I started this thinking that we'd get to see detective stories, where I could solve cases together with the heroes. The cases were, although interesting, not of that sort. They all made sense, but the audience often only got to see the clues at the time Li Lianhua or Fang Duobing revealed them to their co-characters. The cases themselves were overshadowed by the overarching plot relatively early, so for me, they did not have too much merit by themselves, and only served as a vehicle to move the story forward.
The overarching story wasn't that complicated, we got to guess the main villain quite early, and some of the plot twists weren't that twisty for me.
(Also, the main plot point -- evil people from a defeated foreign country try to overthrow the mighty and just and overall better [China] and fail -- is typical Chinese nationalist fare.)
What makes the story interesting, is the journey of Li Lianhua, both in the past, which is revealed to us in increments, and in the present -- Li Lianhua, who is terminally ill and is pulled into the Jianhu after ten years of solitude, whose journey is one of finding closure, of forgiving or avenging, of finding meaning in life and death.

A plus, for me, is also that the series has little romance -- most of it finds it conclusion within three episodes or so around episode 20 (they decide their romance will stay in the past only). Unfortunately, most female characters' motivation still circles around love, more on that see below.

The story unfolds over 36 episodes, which never drag or feel rushed. The series kept my interest throughout -- the pacing was always just right.

THE CHARACTERS:
Li Lianhua is a wonderfully human character. He is flawed, he lies, he deceives but still seems to be a person who has his values he lives by. He is a miracle doctor and a horrible cook. He is someone who pushes others away, and it's never quite clear if it's to protect the other person or himself. He is selfish in his last decision, and at the same time sacrifices his life (essence) for others over and over again. Li Lianhua is world-weary but can still find solace in the little joys in life and seems to believe that most people are ultimately good.
Li Xiangyi was young and inexperienced. He trusted wholeheartedly -- but also judged hard. He thought he was the most important person in the sect -- and died because of it.

I also loved the other two main characters -- loved their banter, of course. They both had their distinct personalities and unique goals. Fang Doubing and Di Feisheng had good character development -- more time to show their personalities and their inner life would have been even better.

The one thing that irked me for the most part of the series was the portrayal of the female characters. Their motivations mainly circled around "love" (or a version thereof), and usually, they had no agency without a man. Let's look at the four most prominent women:
Jiao Li Qiao: Her motivation for anything is to get Di Feisheng as her husband. That's it.
Qiao Wan Mian: She is important as the past love interest of Li Xiangyi, who waited for ten years for him. Later, she gets a bit more agency, but it remains half-hearted. Has she left Zijin or not? Why does she take his Sect leader token but does not take on the role herself? (He is obviously still the sect leader later.)
Master He (Fang doubig's mother): She's the only woman without an interest in pursuing another man; the only one who is shown with significant skills who can contribute to the fight. She is also the only married woman, and the only middle-aged woman, so it's probably just that she's "too old" to be a potential love interest who can be heroically disregarded.
The princess: Her interest in marrying Fang Doubing is somewhat understandable -- as a princess she lives a highly regulated life, and probably knows that the only chance to get a bit of freedom is as a married woman. (Of course, her interest has to take a backseat next to her fiancé's desires.)
There's also the young girl who we first meet when she disguises herself as a man -- she could have easily been a cunning woman with a network of informants or a vast library. But no! She always gets her information from her grandfather and she is allowed to bring Li Lianhua to her brother for treatment.

That's enough of a rant for this review. Let's close with another excellent aspect:

THE ACTING:
I did not find one actor unsatisfying. The minor characters were all right throughout.
All three main characters were portrayed incredibly well. Especially Chen Yi (Li Lianhua) who needed to show his multi-layered personality without words had excellent micro-expressions. Di Feisheng is probably more interesting than the script itself has provided because Xiao Xun Yao manages to hint for underlying emotions of his character from the first second we get to see him on screen.
And a special mention has to go to Rain Wang (Jiao Li Qiao), who, despite her single-trait character, shows how chillingly deranged Jiao Li Qiao has become over the course of the series.

OVERALL:
This is, despite the one flaw, a series that tells a story about friendship, betrayal and revenge -- and a man who just wants to have a quiet death.
Recommended!