There won't be much talking, though ... (SPOILERS)

Rating: 9/10 (1 May 2008)

P.T. Anderson's film is the saga of the making and destruction of the enterprising Daniel Plainview (Day-Lewis), with crucial bits left out for us to guess. Starting out as a lone prospector, he expands his small fortune by drilling oil, and, for some reason, he adopts the infant son of a fellow oil-driller (a partner it seems) who is killed on the job.
Rather than suspect (as one of the other posters here does) that Plainview takes on the kid to trick prospective clients with a pretty face, I believe that his love for the boy is quite genuine, the sole redeeming feature  apart from his obvious head for business  in the man. His pride, however, grows into downright hatred for other people. We are never told directly why or how, since dialog is pretty scarce and what there is, is hardly to be taken on face value. I think Plainview just plainly hates and fears to be made a fool of and, paranoid as he is, he tends to think that happens more frequently than is actually the case.
As I see it, Plainview's love for his adopted son, H.W.  brilliantly played by young Taylor (I can't tell from the IMDb cast list which Taylor plays the boy aged ten, but he is certainly up there with Jack Rovello  young Ed Harris in "The Hours"  and the boy in "The Bicycle Thief", which is to say, top notch child performance)  remains constant throughout. He is accused by the phony evangelist Eli of abandoning his son, but as we are given no specific reason, I prefer to think that he sends the boy off to a home for deaf children and also to keep him out of harm's way after his accident at the oil well.
We gradually witness Plainview's mental downfall, first when he threatens to cut the throat of a business man who peacefully proposes to buy his oilfields, later when he actually kills Henry  the man who made him believe he was his half-brother - and finally in the humiliation and killing of Eli. Although Eli does not inspire much sympathy, he is killed when he is at his most pitiable in what is indeed a gruesome scene. The murder, however, occurs after Plainview's break with his son, when he is emotionally exposed  this being offered as an explanation of Plainview's enigmatic mind, rather than a defense.
TWBB is a wonderful slow-moving film with a sort of 70s feel to it (I was time and again reminded of Jan Troell's "Utvandrarne" from 1971).