Unlike anime with more time on its hands to properly structure and develop a story, a project of this length can easily survive on its indications of what lies outside the limited run time. In this sense, G-9 manages fairly well in producing a cryptic and initially confusing puzzle of amnesia, monologues and calligraphy-inspired artwork.
The story seems initially confusing but reaches acceptable heights of coherence and quality thanks to later elaborations. It never really reaches a conclusion, but there are enough plot devices to make the viewer imagine a tale of larger proportions. We only get to see the female protagonist, Agarta, fight her way through one adventure taking place in human consciousness (where she slays parasites) but it's quite easy to picture her previous and later experiences, which is all the story needs.
I hesitate to even refer to it as animation since there is little to no movement at all. G-9 is highly experimental in its artwork, relying heavily on calligraphy-styled stills rather than movement; a decision quite likely to infuriate audiences. Does it look good? Well, the visual section of G-9 comes off as a double-edged sword. On one hand it features beautiful and detailed stills as well as a distinctive approach, but on the other hand, it fails miserably in its action sequences. In the end, the original and interesting "animation" is bound to lose its charm.
In shorter movies, rather than asking "are the performances good?" a question of higher relevance would be "Do the voices suit the characters?”. I'd like to proclaim that they most certainly do but despite Agarta being mysteriously pleasant to listen to, the rest of the soundtrack is far from impressive with sloppy sound effects and poorly applied songs that don't fit the material very well.
Agarta slays parasites that reside in human consciousness and each time she embarks on a new quest she loses her memories. Once they return she's ready to get the job done and the reward she receives after a successful task is not money like one would expect. Instead she receives old memories in a gradual puzzle of self-discovery. Just like the story development, characterization in G-9 is vague at most but manages to be both interesting and, above all else, sufficient.
As much as it is memorable and fascinating in its own peculiar ways, G-9 suffers from severe problems that turn a story of potential into a decent watch. If you can handle an anime that barely deserves to be called animated, as well as a story that relies on vague indications more than anything concrete you might want to give it a chance. To be absolutely honest, however, I watched it solely because it looked different and if that's what you're after it will suit your tastes perfectly.