Having seen it, I'm not so sure. It's about an oil man in the early days of the Texas oil boom. We see him start with nothing at the start of the film, and build up to a massive fortune. The only problem with the film is that Day-Lewis' character was hard to like. He is extremely focused when it comes to oil, and has difficulty relaxing round other people. He seems more intent on using them (in a comparatively reasonable way, you might argue) than liking them.
This made it difficult for me to like the film. I was left wondering how he was so successful, given his seeming lack of inter-personal skills. It also made me wonder how Day-Lewis got nominated for an Oscar. He didn't make the central character particularly interesting or likable. Given that the film rested on his character, I wondered what I was missing that others obviously saw!