Differents
MOVIE vs BOOK
Between the story of the film and the book there is a difference in the ending.
Also, in the movie, Dorian's life is shown 25 years after Basil's death and his escape from London.
Twenty-five years later, in fact,
Dorian returns and doesn't appear aged by a single day.
Nevertheless, he is a tormented man and he is haunted
by his past and constantly mocked by the abominable
monstrosity locked up in his attic.
One day, he meets Emily, Henry's daughter.
While there are rumors in London that Dorian may have made a deal with the Devil, Henry decides to expose his daughter's mistress.
Only the love for the Henry Wotton's daughter will be able to redeem him and undo the evil effects of evil.
As we can see, Harry's daughter doesn't exist in the book.
so...
IN MY OPINION
sometimes speeches can be difficult to follow, but they "take" you very much.
you can understand them by looking at the context.
I would recommend it for sure, you should read it at least once in your life!
I personally prefer the book to the movie because it's really well written
and transports you into that story as if you were living it.
So... in summary, I would advise you to read the book first, and then, if you like, to watch the film.