After having seen more than half of all episodes, I can confidently say that The Longest Promise is truly a great drama. It's indeed strong in all important aspects:

– Storyline

While it takes an episode or two to fully understand the setting, from then on it's a captivating story with good setups and payoffs, never letting plotlines drag on for too long but also not cutting interesting story elements short.

– Characters & casting

The stars of the show, Xiao Zhan as Shi Ying and Ren Min as Zhu Yan, are the heart of the show. Shi Ying is the tragic center of the story, while the character of Zhu Yan adds the necessary sweetness and a bit of lightheartedness to the story. Especially Xiao Zhan's performance of Shi Ying brings a lot of nuance and heart to the character.

The supporting cast is also very strong: they are well acted and all have their own motivations, ambitions and struggles. They are all written 3-dimensional and make the world and its inhabitants seem more alive (with the only exception so far being the Ice Clan).

– Visuals & CGI

This series is simply beautiful to watch. Sets, costumes, lightning, fight choreography, "magic", CGI background and creatures - they are all masterfully done and really work well with each other. For that alone it's a great watch.

– Music

I often don't notice music, even when it's well done. In this drama however I often notice music in a positive way, consciously realising that it improves the scene I'm watching even further and motivating me to go back and watch the scene again.

All in all a great drama to watch for any fantasy fan, and definitely a must-watch for any xianxia drama fan.