A high-quality series with dynamic scenes, action in almost every episode and no wire fu. Chang'an life, architecture, and crowd scenes are well covered. I can't comment on the historical accuracy, but the attention to detail seems more thorough than in other Chinese series I've watched.
The show has many pros and the script is not one of them. The plot twists are predictable. They focus on the main character until the last episodes, where the focus shifts towards the secondary characters. As a result, it is not clear who to feel for and why.
It is commendable that there is no division into good and evil. However, there are so many characters and not one of them opens up completely. They try to use flashbacks, but it doesn't work well: here are some tough guys today, and here's a five-minute dive into the past. Now I know them well enough to drop a tear! It would be easier to sympathize with Zhang Xiaojing if he was the main character in more than just the first 2/3 of the series.
The last 1/3 of the script seems to have been censored and rewritten due to some political reasons. The conversations in favor of the poor look ridiculous. Officials lecturing the emperor in the presence of the crowd, seriously?
In short, the series raises the quality standards for subsequent shows. It's nice to watch and never gets boring. Personally, I won't watch it again: it doesn't evoke any deep emotions because of the flaws mentioned above.