This movie is, to put it mildly, an experience. If you go in expecting things like fleshed out characters, a cohesive narrative, or even a three-act structure, you will be left frustrated and irritated. Instead of anything resembling a movie, Prisoners of the Ghostland is more of a collection of scenes and moments without any kind of logic or traditional plot applied.
There is a concept of a story: Hero, a bank robber, is tasked with rescuing the Governor of Samurai Town's "Granddaughter" from the Ghostland, a cursed place, blasted and scarred by nuclear radiation. Hero is outfitted in a leather suit with explosives that will detonate if he, in any way, goes against his orders. With Hero setting off in a child's bicycle, the adventure begins.
As others have said, the plotting and pace are bizarre. Nic Cage spends a good chunk of the first half unconscious, having repeated flashbacks to the failed robbery that led to his imprisonment, and his guilt manifesting in visions of a child who was killed on that fateful day. These flashbacks recur through the entire movie, even well into the climax. Granted, the sight of brightly-colored gumballs flying through the air in slow motion is beautiful, but after the sixth or seventh time can become a bit much.
Similar to Cage's previous genre entry Mandy, almost all of the action and chaos is backloaded onto the second half of the story. This is where (in my opinion at least) the movie redeems itself. As a huge fan of Tak Sakaguchi, seeing him face off against Cage is worth the price of admission alone. Even though Sakaguchi does most of the heavy lifting on the action side of things - especially when facing off against a dozen enemy samurai - Cage does a decent job holding his own, especially at his age. As carnage unfolds in all directions, Sion Sono's style comes to the forefront, with gorgeous imagery and bonkers over-the-top violence that the director has become known for.
In short, I really, really liked this one. I even pre-ordered the blu ray the moment I left the theater. However, every negative thing you've been told about Prisoners of the Ghostland is accurate. Whether it was due to time or budgetary constraints, it barely feels like a finished movie. There is no flow to the story, characters come and go from the story without reason, and the movie can't even respect its own internal logic.
With that said, your enjoyment of this will be directly proportional to how much/little you care about conventional filmmaking, and whether or not you can enjoy an unfinished mess that features nonstop sakura blossoms falling while Nic Cage screams "TESTICLLLLLLE" to a crowd of confused onlookers. In other words: The critics and other reviewers are all correct: This is bad. Really bad. Unbearably and oppressively bad.
But it's MY kind of bad.