I am really shocked to see low-scoring reviews for this drama. It has everything you want. It has bromance, romance, and action. The acting is great. Both lead and support actors/actresses are nailing their parts. The pace of the drama is realistic. It is a modern drama, and as a result, nothing magically happens. It takes time for emotions to be developed and mature.
If you follow the pace of the drama, you will cherish every little development between the leads. I believe people who drop this drama or don't find it satisfying are the ones who are skipping along the episodes and missing important hints.
My advice is to take your time watching this drama, experience the lead's ups and downs with them, and you will have a magical time riding their emotional waves. This is a masterpiece.