What I think is most interesting about Christopher Isherwood's books that I have read thus far is how he describes the inter-war years in Berlin. 

The sense of foreboding, the burgeoning anxieties felt by the characters regarding the rise of Hitler is almost tangible. This is tempered by the characters' individual colourfulness and eccentricit—

I liked Goodbye to Berlin, Sally Bowles was an interesting character and it's wild (excuse the pun) how she's based off Olivia Wilde's grandmother. She was your typical pretty little rich girl who could escape back to her own life whenever she wanted....just like Christopher himself who was pretty upper class and English. 

The ending was pretty emotional as many characters either flee Berlin or are imprisoned under the Nazi regime. The discussions that Christopher hears between various people in the streets who believe that Hitler's government would only last months was frankly haunting.

Aside from Sally and Christopher himself, the other characters didn't really stick out as much to me, but I did like it all the same.