The play Pygmalion, by George Bernard Shaw is, like the previous post accurately stated, primarily a social satire that belongs to the genre of Romanticism, and most specifically, to the form of Comedy of Manners. Within this genre, society is often mocked particularly by the way that the upper classes act and think.
One most keep into consideration that GB Shaw is an Irish playwright who produces pieces for a very complex British Victorian audience. Victorian society is notorious for its classicist nature, for its hypocritical values, and for its 'holier than thou' attitudes. When we take this into consideration, we can safely argue that Shaw literally laughed at the English Victorian audience right in its face by pointing out the shallow nature of their judgement of other people.
You see this creature with her kerbstone English: the English that will keep her in the gutter to the end of her days. Well, sir, in three months I could pass that girl off as a duchess at an ambassador's garden party. I could even get her a place as lady's maid or shop assistant, which requires better English. That's the sort of thing I do for commercial millionaires. And on the profits of it I do genuine scientific work in phonetics, and a little as a poet on Miltonic lines.
The central theme of the play revolves around making a peasant girl look portrayDuchess in an upcoming fashionable event. In the process of transforming Eliza, Shaw irreverently points at the coarse and terrible image that the lower classes have of the upper classes by making jokes at the way Eliza should pronounce words and use specific mannerisms. These words are exaggerated and made to look ridiculous. The mannerisms are meant to mock the aristocrats. The language used by Eliza and her peers throughout the transformation process just adds salt to the wound: It brings the upper classes spiraling down from their self-made pedestals.
Therefore, far from portraying the English as tolerant, kind, and intelligent people, Shaw shows us how easily to deceive they can be if only you make someone look and sound the way an aristocrat is meant to look and sound. Because of this clear attack to a society that accepts no criticism, Shaw obtained mixed reviews about the play. It is not so much because of its form, but because of its central message: Shaw seems to have been quite interested in pointing out social flaws, and this is obviously something that, in a shallow society, will not transform into a vote of approval.