Will Smith has a reputation of being involved in generally pretty good films and this one was not an exception. I feel as though Smith is a very versatile actor and Seven Pounds shows some of his better dramatic work in my opinion.
The movie begins with Smith making a phone call to 911 emergency services stating that he wants to report a suicide and when they ask "whose suicide," he responds "mine."
Then the movie completely changes gears and doesn't refer to what that scene was about for nearly the entire film. I like how they did this because they don't narrate it, they show it by the actions of Ben Thomas as he begins gathering intel on various people in the community. He is presenting himself sometimes as Tim Thomas, an IRS agent - who is actually his brother (in the movie.) It isn't immediately revealed that he actually is not an IRS agent, but needs his brother's credentials to gain access to these people.
He primarily uses this false identity to be able to speak to Emily Posa, a woman who is in the hospital suffering from a heart disease that will eventually result in her death. At first his actions seem heartless and cruel because she is dying, and he is there to talk to her about back taxes that she owes to the government.

However, it is all a ruse because he doesn't actually work for the IRS, never has. He is actually determining whether or not she is a legitimately good person.
He does something similar while investigating Ezra Turner, who is played by Woody Harrelson. Ezra is a blind vegan who works for a meat distribution company. The initial scenes are very powerful as Ben phones him up and is incredibly mean to him.
I don't want to ruin too much of the story but the reason that Ben / Tim is looking for these two as well as 5 other genuinely good people is because he was driving and texting when he crashed his car and hit an oncoming vehicle, killing 7 people in the process. This is the reason for his search, and I will leave it at that because you really should see this movie.