Manga So Bizarre It's Good
This is a slow burner, making the Character Development and arduous battle scenes all the more effective. Despite, and at times in spite of the author's blatant fetishes for Most Common Super Power and Ludicrous Gibs, Gantz has all the right elements of action, horror, and suspense, as well as a pristine art style that captures the story vividly. Many cliches are introduced, but are mostly handled well. At times, the cliches and tropes are even effectively deconstructed.
The Anyone Can Die / Back from the Dead quality of the storyline will definitely keep you on your toes.
Looking like Light Yagami and acting like Desert Punk, Kei Kurono is the main character who is initially meant to embody a standard selfish, horny, disaffected teen for the first volume or so. Don't worry, he gets better. Given the Loads and Loads of Characters, you are liable to have a couple of favorites. I personally enjoyed Kato, Kaze, Host Samurai and Anzu, to name a few.
Besides the overarching mystery, the series' juice lies in the astonishing fights. Ordinary people, fleshy and terrified, duke it out with creatures that have heavily overdosed on Bizarre Alien Biology. Body Horror ensues, naturally. The humans are so unprepared for the aliens that it seems almost like a procedural, but then the survivors slowly start to figure things out and levels in badass are taken. Even with the science fiction elements and the fact that just about every female character of relative importance is endowed with pornstar proportions, the mood of Gantz is eerily realistic, and thus very nerveracking.
I only have two big complaints:
1) The ending is ridiculously anti-climatic. Felt like the author just wanted it to be done, even if there were several dangling plot-points that never got resolved.
2) Everybody is an Ungrateful Bastard. The author clearly has a low opinion of humanity, which shines through thematically. From the first issue to the last, everybody who isn't an important character is a Jerkass to some degree. Also very ridiculous.
You never know what to expect, though. I found Gantz very exciting, if not slightly annoying. Of course, that it basically runs on Nightmare Fuel and Male Gaze means it might not be for everyone. I would highly suggest reading the manga over the anime.
Manga Kei Kurono The Manga
Gantz is one of my favorite manga of all time. Almost all of it is due to its protagonist, Kurono. Who is by far the most entertaining character because he's such a scumbag. His antics are so unexpected and audacious that he comes across as an Unsympathetic Comedy Protagonist. It also helps that he's oddly relatable and likable. His Classical Antihero status is more unique compared to most uses of the trope today where instead of the flaws revolving around insecurity and lack of confidence, it's about his selfishness and jerkassery. What helps keep him relatable besides his flaws, is his honest and cynical perspective. Kurono's a kind of character many stories today usually use to be hated, but here he's our hero. One that I fully sympathized and rooted for from the start. It helps that he does develop into more altruistic but still anti-heroic character. To me, he's one of the best and one of my most favorite characters of all time.
The rest of the cast doesn't really become memorable asides from him and Kato until a lot later. Once that happens though, the team is likable and cool. The biggest strength of the storytelling is we don't just see their fights against the aliens, we also get to see their lives when they're not total badasses, giving them more depth and relatability. Suzuki, Reika, Kaze, Sakurai, and Sakata are awesome. Izumi's decent but it felt like he didn't get enough focus to be impactful.
There's also Tae, a well-written Satellite Love Interest, as she's the catalyst for Kurono's development while having an established personality. And her Hollywood Homely status is unique for a hero's girlfriend in anime and manga which I appreciated.
There's also some nice Graying Morality that comes into play over time and I like how the story doesn't try to get you to sympathize with one side over the other most of the time, it lets you interpret it how you want.
I'm not a fan of excessive gore, but due to the context and art style, I actually enjoyed the over-the-top violence and horror elements. Speaking of the art style, it's jaw-dropping.
As for cons, at times it feels like the author sorta came up with some of the plot developments on a whim and then either got bored of it or realized how out of place it was and just never addressed it again. The dialogue at times can be very cheesy, though I do like how it uses its art and facial expressions to tell a story rather than rely on text. While I do like the final arc, I feel the ending does miss the mark a bit in that it can feel a bit like an Esoteric Happy Ending because of how we don't get to see the aftermath to address the effects of the final arc.
Overall, I highly recommend the manga. As for the anime, I'd only suggest watching it simply for Kurono's English VA's amazing performance and for some Adaptation Expansion.