In FOTR, we see Boromir as proud, skeptical, and pragmatic. He is willing for the Sword that was broken to come to the aid of his people. At the Council of Elrond, Boromir is skeptical of Gandalf and the Elves, virtually all of his people are, as the Elves are skeptical of men, Dwarves of Elves, etc. Middle-earth is full of mistrust.
He is bold and arrogant, blowing the Horn of Gondor as they leave Rivendell, he is chastised but states that he will not go as a thief in the night. Even today we are taught that if you project confidence and self assurance when we walk alone through a parking lot at night, you will reduce risk of attack. If you act suspicious, you will be watched and followed. This is another thing he has been trained for, as a warrior and leader.
In Moria, it is Boromir who covers the party as they escape from the various chambers. He is the one who closes and holds the doors being them, the one who stands to fight until Gandalf tells them that swords are of no more use. Subtly, we are shown that he already has recognized that Aragorn must lead the group, he has accepted the role of final line of defense, as has been the Role of Gondor in the last years.
In the end, he tells Aragorn what he has done and asks forgiveness, stating that he did not understand, but now does, and he reports what he has seen to his commander, as a good soldier, and he asks Aragorn to save his people because he cannot. His final words are of his home and the people of his homeland. He is dutiful to the last.
Boromir's role in the Quest was vital. Without him and his fall, the Quest would have doubtless failed. Frodo would not have been able to make up his mind to go on alone when he did without Boromir's attack. A large party would not have been able to cross Mordor undetected. Without the breaking of the fellowship, the Rohirrim would not have won at Helm's deep, the Huorns and Ents would not have come to help and the Rohirrim would not have gone to Gondor's aid.
Strong-willed, dutiful, proud, arrogant, masterful, loyal, a good leader, a good soldier, I see him as all of these and more. A man with serious flaws but a good heart, not a saint, never a saint. He was a man of his time and place who had doubts, fears, and the weakness of them.