Since it's been a while that I have watched this drama, I will directly jump into my seven criteria without wasting too much of your time (please refer to my definitions below).

1. "Sleepness Night": 4/5 ★★★★☆
This drama is very well made with the atmosphere, lighting, and shots of a movie. While romance plays a central role, this drama's dominant theme is political conspiracy revolved around Male Lead's family and the Female Lead's relentless effort to save his master. The first arc at which our main characters gather to retrieve the "Shan He Tu" extremely nerve-wracking. Most shots are taking with natural sceneries; the action scenes are enthralling, and you quickly start to fall in love with all characters. The later arcs started to have plot holes and became slower but still overall thrilling.

2. Emotional Rollercoaster: 5/5 ★★★★★
This drama has three very different couples. All three go through their own unique development, showing that every love story has its flaws and selfishness. My favorite pair is Wen Si Yuan and Shen Man Qing. Their love is mature, direct, and just very sweet at times. I have seen Zhou Ting Wei playing at Ashes of Love but was not that impressed with his role. But in Love in Between, Wen Si Yuan is a character you just cannot resist. Despite playing the silent Shan Shui Du Master, small facial expressions such as one jump of the eyebrow, teary eye, or pressing lips, reveal thousands of words. I enjoy that this show is using the original voices of the actors. Zhou Ting Wei has the perfect voice.
The main couple Zuo Qing Ci and Su Yun Luo are more painful to watch. While ZQC sacrifices quietly for the FL, FL had to learn to appreciate the ML while balancing off her duty of saving her master with her feeling towards the ML. The ML's behavior reminds me of Si Feng from Love and Redemption. His crying scenes are breathtaking. And he cries a lot!

3. Natural and Intelligent Story Telling: 3/5 ★★★☆☆
While the start of this drama was great, the later arcs were less smooth. Some development (such as tragedies and turning bad of supporting characters) felt forced and a bit unnecessary. I wished they would have stuck to the original external story.

4. "Loveable supporting Role": 5/5 ★★★★★
Most of this drama's characters are extremely well-written and developed. Besides the couples, my heart was struck by the anti-hero character Gui Tong Zi, played by both Wang Zi Run. His background story, acting, action scenes remain strongly in my memory and is one of the best anti-heroes I have seen in C-drama.

5. "Proper Pacing": 4/5 ★★★★☆
The drama could have shortened the last arcs.

6. Technicalities: 5/5 ★★★★★
Excellent and really nothing to complain about. Beautiful shots, great lighting despite that over 70% of the shots are taken at night. It gives the dark atmosphere that this drama needs.

7. Solid Finale: 2/5 ★★☆☆☆
That's really a shortcoming of this drama. It has a happy ending, which is really not logical. All flags and plot developments indicate towards a sad ending but it did not. I am tired of great drama trying to please the audience but forcefully ends happily. If this drama had ended tragic, it would have been so much more convincing and suitable for this show's overall tone. They should learn a bit from shows like Goodby My Princess.

Overall, my verdict is 8.5/10 given some of the shortcomings. I would still highly recommend the show: great actions, interesting characters, and an appropriate balance of politics, Jiang Hu conflicts, and romance.

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Kotori's drama review seven criteria definition:

After having watched many dramas and also written several reviews. I have detected that I rate dramas based on specific patterns. I formulated those into seven criteria.
1. "Sleepless Nights.": how much I have the urge to binge-watch this drama.
2. "Emotional Rollercoaster": the degree of how much my heart was moving from the acting, scenes, and story development (e.g., in pain, pounding, fluster etc.). The degree on how much I care about the fate of the main leads.
3. "Natural and intelligent Storytelling.": how logically the story was able to proceed and the roles are acting within their characters. I don't have a thousand question marks when watching the drama. The feeling that the makers take us viewers seriously and that we do not always think that this looks fake.
4. "Loveable supporting Roles.": how much I love and care about supporting characters. They are not merely tools to help the main characters but are 3-dimensional and have the proper motivation behind their actions.
5. "Proper Pacing.": how well the drama is pacing and not watered down to fill the number of episodes.
6. "Technicalities": professional camera works and shots, fight scenes, color grading, lighting, editing, music, sets, costumes, use of CGI etc. I try to grade this in relation to the drama budget, so a low-budget drama can equally get a high score when used at the right place
7. "Solid Finale": how properly the drama builds dramatic and finishes with a satisfactory ending. I have just watched too many dramas that start to lose their grip around half or 2/3rd of its way