Infinity War is a massive achievement for the Marvel Cinematic Universe. The movie has been a huge hit with critics and fans alike, but there are some faults with the storyline that have basically been overlooked because of the grand scale of the movie. Which leads us to Gamora's arc in Infinity War. Some are arguing that her addition to the story is actually a giant plot hole, while others maintain that her story was properly used. There are major SPOILERS for Infinity War below, so read ahead at your own risk.
The Guardians of the Galaxy play a large role in Infinity War right from the start when they are introduced to Thor after Thanos destroys the Asgardian refugee ship. Gamora and Nebula were always going to have more at stake than the rest of the new crew because of their close ties to the Mad Titan, which makes Gamora's decision to go directly to Thanos a bit fishy. The Guardians split up, half of them go with Thor to build a new weapon while Gamora volunteers to go directly to Thanos, knowing better than anybody what he's capable of.
This is the plot hole that MCU fans have been discussing. Why would Gamora go directly to Thanos, knowing everything that she does? The character practically gives Thanos the Soul Stone in exchange for Nebula's life. Now, the storyline of Infinity War as a whole moves forward because of Gamora's sacrifice, making it possible for Nebula to end up on Titan with Iron Man after Thanos snaps his fingers in Wakanda. Sure, Gamora's arc may seem a little clunky, but it pushes the movie forward, raising the stakes and showcasing how ruthless Thanos truly is.
Gamora's sacrifice is an important one for the tone of Infinity War. She knows her fate but wants Star-Lord to kill her if she end up being taken by Thanos, which he tried to do. However, Thanos had already secured the Reality Stone by that time and decided to plot a trap that would play off of the emotions of Gamora. Thanos' plan works out and he ends up getting the Soul Stone after torturing Nebula in front of Gamora. While some cry that Gamora's sacrifice is a plot hole, others just call it continuity within the MCU.
Nebula and Gamora cement their sisterhood bond in Guardians of the Galaxy Vol. 2, which really goes a long way in setting up the events in Infinity War. While the story may not be perfect, it does an excellent job of tying 19 movies together and utilizing an incredible number of superheroes all in one place. As for the fate of Gamora, that isn't clear at this time. Some MCU fans believe that she is trapped in the Soul Stone along with the rest of the disintegrated superheroes. We'll just have to wait and see what the Russo Brothers have concocted for the still untitled Avengers 4 next May. You can read more about the supposed Gamora plot hole over at Digital Spy.