City Lights is a light hearted comedy on the surface and a much more subtle melodrama at it's core. His pioneering social commentary is common place in all Chaplin films, especially The Great Dictator and The Kid. This film is so obviously a political movie that it opens on a statue representing justice outside of the local courthouse as it is being revealed for the first time.
The message of the lower class being forgettable and disposable is repeateded throughout the film but most powerfully at the very end of the film. The Blind Girl is back from Brazil for her surgery and the Tramp is out of prison, but ultimately she is unable to accept him and only placate him with a smile as he eagerly collects any attention she is willing to pay him.
Chaplin the first champion of the downtrodden and he inspired Pasolini, DaSica, Almodovar and countless others.
Overall the film is impecably put together - everything works. The quirky coincedences lead our hero into situations which are funny, entertaining and yet still put forth a much more sophisticated tale.
If you haven't yet done yourself the service of watching a Chaplin film this one would be a great one to start on. Infact I am a believer that all Chaplin films are worthy of starting on as The Gold Rush and Modern Times are just as good (if not better) as any of the other ones I have listed already.
He truly is a genius and this is one of his best films, which is tough because they are all really good.
75 years later and he is still timeless and as good as anyone else.