Don't read this play if you or your family have a history of drug addiction and/or alcoholism and you don't want to be reminded of it. This play is about the disintegration of a family whose members are, variously, addicted to drugs or alcohol; tormented by the failure of their dreams; or dying from disease on top of the other problems.
That said...this is a fascinating play with a explosive end. The first three acts are so quiet in comparison, in their depiction of the Tyrone family's individual miseries, that I was caught off guard and astonished by the end of Act IV.
I liked the play well enough after the first three acts, but I think I was vaguely disappointed and bored by the family members' endless tiptoeing around the sources of their misery and shifting back and forth between sniping at each other and trying to pretend nothing is wrong.
Everyone who reads about this play knows it is autobiographical, with the Tyrones representing Eugene O'Neill's family and the protagonist Edmund Tyrone representing Eugene O'Neill himself. With Eugene O'Neill being a famous playwright, you might think Edmund is the most interesting character; but I say no, not really. I find his older brother Jamie more complex and therefore more interesting. I'm not entirely sure why yet--I want to study Jamie more closely--but I think it has to do with the difference in Jamie's condition from Edmund's and Mary's. Jamie is a heavy drinker and possibly an alcoholic, but not terminally ill like Edmund or a drug addict like Mary. And since Jamie is out of favor with his father (who considers him a ne'er-do-well) and is receiving less attention because he's not dying, he is more distant from his family and often acts as a cynical observer. At the end, he seems the most emotionally tormented member of the family, certainly more tormented than Edmund.