Daniel Day-Lewis's performance is generally regarded as a brilliant performance by many, but there are also dissenters as well who criticize it as being an over the top performance. Well I think it should be examined for both of these qualities actually.
This is one performance that can never be accused of playing it safe, Day-Lewis here goes for something completely outside what most performances try to do. Day-Lewis creates an entirely unique creation in Daniel Plainview with his whole manner, as well as his John Huston voice he uses in the role. The use of the Huston voice is certainly a bold move, and it is one that work well in Day-Lewis' favor since he is entirely consistent with the voice, and it just works incredibly well for this larger than life character.
Now in addition to his voice he uses he does also take on many mannerisms that further suggest Plainview as a character. The little things he does with his mouth, and his distinct way he walks in the part. I will say again these mannerisms are very well done, and do seem to be part of the character, and work very well in favor of his performance. Day-Lewis was clearly trying to recreate someone from the period, and Day-Lewis certainly does that incredibly well.
The sheer force Day-Lewis puts in the role is incredible. He controls every single scene period. There is never a single question, because Day-Lewis creates an overpowering presence throughout the film, that refuses to be challenged by anyone, even though Paul Dano tries as the town preacher Eli. Day-Lewis creates the right intense power in every scene, especially in his speeches to the towns people that perfectly suggest the overwhelming authority Plainview creates.
Now Day-Lewis is also effective in his creation of the greed in Plainview, and showing the intensity of his personality. He is best in his scenes with his "brother" where he tells of his true feeling about people. Day-Lewis brilliantly shows the insight into the mind of his character, and makes his greed something that cannot at all be swayed by anything or anyone.
The strongest aspect of his performance to me though might be with his adopted son H.W. It is interesting because this is where Day-Lewis does display some subtly. It is fascinating because he is able to suggest that Plainview does not only think of his son as a business tool entirely. Day-Lewis does carefully show he does have a love for the boy, even though Plainview does his best to hide it, Day-Lewis lets it show subtly in certain moments of the film.