The City in Glass is a story of grief, extended in an order of magnitude when it is a whole city being grieved across centuries. Nghi Vo's mastery of language and ability to create sympathetic characters outside of the boundaries of good and evil allow for a deep exploration of what it means to miss not only people, but the place that was created by their presence and the essence of their having lived.

The slow progression of the relationship between Vitrine and her angel is wonderfully fleshed out. The detail in how the pieces of each other each keeps within themselves - Vitrine voluntarily and her angel as involuntary penance - slowly bring the two of them together, poisoning the angel into vulnerability as he learns to love what he destroyed and poisoning Vitrine into loving him.