Peter Carellini’s review published on Letterboxd:
To call someone inherently evil, is that a cop out? A grave admittance of humanity's capability for darkness? A solemn understanding? Was the almost demonic oil baron Daniel Plainview present in the quiet, mineral prospector Daniel Plainview, ready to come out, or did his new life corrupt his old, as we see in the descent to madness over the course of the film? We'll never know. But he's grown too powerful to even combat, so the best course of action is to let themselves be pulled into their own black holes. Don't worry, though - those similar will be pulled in, and those virtuous will get out. Throughout There Will Be Blood, the similar demons and the virtuous come in the form of preacher Eli Sunday and Plainview's adopted son, H.W. These two are the moral extremes, yanking Daniel in a brutal tug-of-war, but to hell with that, capitalistic Daniel Plainview is his own man and system - he's gonna dictate how he wins this one, regardless of the players. You better believe there'll be blood, keyword being will, as Daniel will continue to grow more bloodthirsty as he keeps devouring himself by his own ruthlessness and sheer inability to connect with people. It's a disquieting struggle to watch, because the film never pretends Daniel doesn't deserve damnation for his sins, yet at the same time, we...very deep down, kind of appreciate his insane drive? His having no qualms in fending off those who would wrong him? Though we jump ship at the apex of his insanity, ready to leave this monster behind. So yeah, I think this is the ideal, no holds barred portrayal of the American Dream. John Steinbeck is clapping his ass off in his grave.
I don't need to expand on Daniel Day Lewis in this film, as the raves you've probably heard about his acting here are all true. But I will say his achievements have always lied in his creation of larger than life figures, as is the case with Daniel Plainview here. Even if the other elements of the film sucked, he'd still be well, well worth it to watch - along with some gorgeously created 1900s Texas vistas, twisting that Americana iconography to a desolate, spooky existence. And Paul Dano, whose genius lies in how he coats his character with a paper thin righteousness that hides his horrible hypocrisy and manipulative dogma, is the other side of shadow waging war for the American soul. No less insane, no less destructive, despite what he may have you think.
Like H.W, we are the lives at stake in that war, and we need to run - blood is coming.