The best description for this movie I came up with is: A steampunk re-imagining of JM Barrie's characters and Neverland, in the function of a prequel, infused with a Harry Potter theme."
Let's break that down a little now:
Steampunk is a sub-genre of science fiction literature that features steam-powered machinery. Although it often takes place in the future, the cultural norms, language, and fashions are inspired by the Victorian age, so they along with the steam-powered machinery create an interesting tension between the past and the future.
The story does feature a flying ship (which is part of Barrie's classic, but also has a very steampunk feel) as well as cable cars and hot air balloons, and all the portions where the orphans are mining for Pixium.
And the major players like Peter Pan, Captain Hook, and Princess Tiger Lily are all there in Neverland to remind us which story we're supposed to be caring about, but the actual story takes place before Pan and Captain Hook are sworn enemies. In fact, they are allies against the infamous Blackbeard. This is a clever insertion, as it is an allusion to Barrie's speech at Eton College, in which he identified James Hook as "Blackbeard's bo'sun" [boat swain=ship officer]. So the story of the characters is a prologue to the one we all know, but it's anachronistic because the setting appears to be World War I, which is a bout a decade after Barrie penned the play.
Aside from the gritty war-torn London setting (instead of the romanticized Edwardian Kensington Gardens version we usually see) is the inclusion of modern rock songs by The Ramones and Nirvana. Obviously those songs didn't exist for another 60 or 80 years, respectively.
Lastly, the thread of maternal love isn't exactly new; Barrie's text is wrought with maternal symbolism, obviously reflecting his personal life, but the aspect of Peter's mother being a warrior against the evil Blackbeard and sacrificing herself for the safety of her infant son, and then Peter seeing her spirit and making his peace with her death just reeks of Harry Potter.