This graphic novel series is based on the original Avatar 2 script by James Cameron, before he decided it was missing something, and decided to move the story of The Way of Water from film 3 to film 2. So The High Ground is canonically "Avatar 1.5". Honestly, Cameron made the right decision. While this graphic novel was pretty good, it didn't have the necessary spark to move Avatar from a "single movie" into a "franchise".
The High Ground then becomes "The Lost Chapter", telling the story of the humans re-landing on Pandora, and Jake's battle for "The High Ground", or space. The premise, and the hook, is having the Na'vi go to the stars and fight in Zero G to fend the humans off before they land. That hook is great, but it's also the reason why this never became Avatar 2. Space is too familiar for sci-fi fans, and we really miss the lush world of Pandora. Still, this story would have been great to see on film. In graphic novel format, it suffers a bit. The Na'vi look even more similar in graphic novel format than they do on film, and the action can be pretty hard to follow. Sherri Smith has done a passable job converting the film script to graphic novel script, but it doesn't have the same cohesiveness as something that began its life as a graphic novel. The page limit also makes things feel a bit rushed. We get all of the action scenes, but very little of the in-between scenes where the worldbuilding takes place. So, as a story, it succeeds. As a graphic novel, it leaves something to be desired, which is the main reason I gave it 3 stars.
There is a lot of good to this graphic novel though. We get a proper introduction to Spider, and we see more depth in his and Kiri's strange kinship. I love the scene where Kiri, instead of subduing an Ikran (Banshee), simply walks up and asks it to be her friend. Neytiri actually has some screentime in this one, though it's mostly relegated to battle scenes. The surprising standout character in this novel is Josh, a hacker who gets some great one-liners. As stated above, the overall story is solid, and a worthy entry to the Avatar series.
Maybe someday, after Avatar becomes a successful franchise, this will become the "Rogue One" of the Avatar series, and get made as a movie. I'd love to see this story mixed with some of the events of "The Next Shadow", as there's some great thematic potential in juxtaposing Jake's development in The Next Shadow with Neteyem and Spider in The High Ground. As of now though, the Graphic Novel is just the wrong medium for The High Ground.
EDIT after 2nd Read: I read it physically, in an oversized hard cover, and need to give special note that when it's printed on a page, the art is astoundingly beautiful.