The book is generally regarded as a classic Victorian pot boiler. It may be, but I prefer the movie.
I like the inclusion of Basil's imaginary masked man stories as a child. In having already exiled Ralph, we see clearly what the father will do if he finds out about the relationship between Basil and Julia. Mannion here is a worldly, genial friend to Basil, introducing him to smoking cigars and talk of sex. He seems to be Basil's salvation. Clara being a child taken in by Basil's parents rather than a sibling seems contrived only for one scene, but it doesn't detract that she is not his sister.
Basil, being only 20, and still at college, makes it far more believable that he would not suspect those around him of being anything but honest and honorable. The idea that the relationship must be kept secret for only three months makes the story move along faster and is more believable.
The incident Basil sees as a child, involving his father, makes his Father's talk of family pride ring false. In the book Basil insists that his father is a good man, though blatantly classist, and cold to his children. In the movie, we know that he is not as good as he wants people to think.
Basil's having to do manual labor, and being shocked at the pittance he gets for it is still a social issue and one Collins did not address.
The inclusion of the child shows Basil to be a much more honorable, moral and principled man in the end than his father ever was.
It's an interesting movie, the acting is suited to a Victorian drama, and I enjoyed it very much.