MissSoybeans

Exactly! She can be immature/childish outside the hospital because, of course, she has just been out of college, and that's relatable for her age (this was what I meant in my first comment), and I thank you @John Smith for adding some clarifications. I find Zhou Ran's character acceptable, thrilling even, in a way where he is creepy, which means we are in for a good show and mystery.

For Liang Muze who is cold and distant, such as in the first episodes while Xia and he are still getting to know each other, I feel for him a lot and I'm glad that the writer had done the research because I have friends who are married to military officers and their husbands have different stories, especially after taking a mission. Some had trauma, and others have anxiety. For example, a friend of mine told me that her husband would not hold her hands in public because according to the husband, the dangers are everywhere, and he needs his hands free just in case. While the other saw how his teammates died or lost their body parts in the mission, so these occurrences can take a toll on one's mental and emotional state even if he/she is physically fit.
Of course, every drama has its downside; the only thing I dislike at this moment is Liang Muze's cousin who resided in an English-speaking country and went home to China, but the English accent is very bad, or maybe it's the dubber who got it worse.

Moreover, those who kept comparing MDG to YAMH, which is also inevitable for us since they have the same genre, just know that MDG was supposedly be released last March, but they held back maybe to avoid comparisons, but here we are anyway.
For YAMH, I love Sandra Ma, and I watched it excitedly, but I have never felt so let down. I felt like the production team for YAMH thinks that viewers are dumb or did not do their research enough because it’s a bit off to let a slim captain play the role. Note that this is not body shaming, I just want authenticity and more respect for military personnel (whom, by the way, spent so much of their time to prepare for war/their mission) since I have observed that Sandra Ma is physically broader than Bai Jingting, which makes the drama and their interaction awkward. He looked like a child and untrained, instead of an ops agent who is used to physical training, missions, and guns which can be very heavy to carry.

I love the drama so far and both leads have good chemistry. I love the combination of romance, action, and comedy in one drama because one can never get bored. Now, I see some of the comments stating that Li Qin is immature as a doctor, but one needs to realize that there are different types of doctors, one with experience while others are in training and recently out of the university. Li Qin falls on the latter because she is a resident doctor, which means a postgraduate and will only be qualified as a practitioner after years of training.
Thus, keep paying attention to the small details since these will make and complete the bigger picture.

Some of us compared this doctor-military romance to DOTS, where SHK was a medical team leader, and you think Li Qin would be that experienced as well. However, in MDG, she is just like that doctor guy (Onew) in DOTS who kept calling SHK his ‘sunbae’. He was also young and inexperienced!

Now for Johnny Huan/Captain Liang, I've never followed any of his drama before but his and Li Qin's acting is fine to me. So, as in the synopsis, he was cold-hearted due to his experience with his best friend/mate who was sacrificed in the mission. He acted like an ass many times towards Xia because he was scared to lose another friend. This does not justify his cold behavior, but he was nice and friendly to his friends and family.

For Dr. Xia’s friend, she may be turning her back on Xia Chu in the future, but Mi Gu has already explained how and why they became friends.
There are a few here who asked how they become friends and I wonder if you really watched the drama or you just have lower comprehension skills?