PT Anderson is a master at what he does. His films don't connect with a wide audience because so much of it requires a painstaking attention to detail. Similar in many ways to Kubrick in that sense. His movies are achingly personal and CANNOT be viewed with anything other than complete attention. If you are texting, cooking, talking to someone or distracting yourself in any way from being immersed by his movies you won't be transported.
There Will Be Blood has such a strong visual impact. You can take a still frame at nearly every point in the movie and you would have a stunning photo. To carry that visual excellence for two and a half hours is astounding. You can watch the color palette, the framing of shots, the lighting, the camera movement and the usage of long shots versus quicker cuts and have a belly full of satisfaction.
From there you can absorb the visuals, enjoy the beautiful marriage of Johnny Greenwood's score to those visuals, and allow the character driven story to take over. The movie builds tension until you get three release points of amazing climax/confrontation/emotion.
In comparing TWBB to PT Anderson's other work, because honestly it isn't fair to other directors to compare their work to his, I'd rank it as his third best work. Magnolia is head of the class, the fastest 3 hrs and 9 minutes of cinema and the most haunting movie I have seen. Punch Drunk Love is a visual masterpiece, a relatively simple story but with the most emphasis on light and color to reinforce the story. Then TWBB, followed by Boogie Nights and then The Master.