The professor assigned the book to the student.
Why would a professor assign a bad book or play to a student?
We have to believe that he would not assign a bad book or play to a student.
The student probably had never heard of this book or play.
But the professor recommended it to his student.
Therefore, there must be something good or interesting about the play.
So, when we read the sentence we understand (it is implied) that the professor believes that there is SOMETHING good/positive/worthwhile about the play, and he also believes that studying the play will benefit the student, and so the professor WANTS the student to read it.
In real life, we sometimes say "There is something about that person that I really like."
That's a statement of fact, but it implies that the speaker believes that he or she would like to find out if that is true by knowing more about the person that the speaker referred to. The word 'something' often means 'something interesting/good/positive', and less often it can mean or imply something negative. The positive or negative implication depends on what is said before or after the 'something' clause/phrase.