Above is a link to the Dateline documentary of Shackleton's journey. I found it interesting to listen to as reading the book allows you to create your own ideas of what happened on their journey, then this kind of gives a better explanation and solidifies their actual experiences rather than leaving it for your imagination to understand.
One thing that stuck that the documentary covered is Shackleton's attitude. During the reading, I got the vibe that Shackleton was a bitter man, torn that his trip may be defeating him. The other crew members called him names behind his back, and he was stubborn. The documentary states that they wouldn't have made it without him, which I think is only partly true. While he was the leader of the pack, and typically called all the shots, there were some poor decisions made on his part as well that led them into terrible situations, such as lack of food. The crew and Shackleton became a team. I don't think that he was the reason they made it, they each played a very important role in that journey. In situations such as there's no way to survive without team work. There was no sole person that made their mission possible, it was simply a collaboration.