The actors/actresses all fit their roles well. The male lead Zi Xuan will seem dull/emotionless at first but that's what is required of his character. You can see in the second half of the drama that the actor is able to portray a variety of emotions.

I like that the drama shows character growth and learning. Zi Xuan is always planning ahead and thinking for everyone's sake. Bai Yao Yao (White Snake) goes from a naive young snake to someone who truly understands Zi Xuan. Xiao Qing (Green Snake) learns what is love very naturally. Ling Chu/Qi Xiao/Monk stays stubborn but is always caring - especially since he's supposed to be Fa Hai (legendary monk who breaks up the main lead's love). Even the heavenly elders realize that they can be wrong and they have their own biases when wishing the best for their disciples.

No one is truly evil and everyone has someone they are willing to sacrifice to protect. You might not agree with how they go about expressing their love, but you can always empathize with them. I think that's the beauty of this drama. By the end of it all, you can't really hate any of the characters.