The movie indeed has its own significance. However, to be honest, on an emotional level, the book and the movie are incomplete without each other. Generally speaking, the book is almost always superior to the movie. Will Smith's outstanding performance in portraying Gardner on a more empathetic visual level has a stronger impact on me than the real Chris Gardner's description of his trials in written form. Nevertheless, the book, which details more than a decade of verbal and emotional abuse, including being raped, etc., makes these struggles and eventual achievements more prominent.
Despite growing up without his biological father (he was raised by his stepfather, a man who was the cause of many domestic violence incidents), he has had a large number of people who have provided him with support and help. From his various uncles, aunts, and cousins as a child, to the military, then the mentors in his early twenties, to the pastor, and even the prostitutes who gave his son money as he rushed back and forth to work to complete his quota of 200+ calls at Bear Stearns.
Is he an angel? No, but he is an example that even when everything seems to be against you, if you are willing to fight against the odds, sometimes help can come from unexpected sources. What's even better is that this guy has given back to the people who have helped him over the years, which should be the definition of wealth for anyone.