Gantz is kind of awesome, but in a weird way. A really weird way. Not "weird" because of any kind of originality, but because of how it manages to be awesome.The plot is extremely lazy with blatant holes throughout. It's mostly about the overblown/unrealistic action, and holy mother of god, is it overblown/unrealistic. Ammo clips are infinite, when actual guns are used. The masses are weak, brainless, and easily influenced cannon fodder, to an absurdly exaggerated degree. "The masses," of course, including just about all side characters. In the world of Gantz, gangsters hang out in toilet stalls and collect people's teeth like baseball cards. Characters lose limbs and just joke about it without bleeding to death. At one point, the crew fights off an army of massive evil Buddha statues. No societal or theological commentary there, just shits and giggles.
This was clearly the product of a creative mind, at least at the outset, but a lazy one as well. It falls apart towards the end, it's full of terminated sub-plots and forgotten characters, and it constantly re-writes its own rules. So why was it not bad? Well, it is self-aware to an almost hilarious degree. Okay, it is absolutely to a hilarious degree. I can't imagine Oku (the mangaka) wrote this stuff with a straight face. The aliens are often ridiculously comedic in their odd design, although they got less so as the series went on. They have zero personality besides some funny quirks and rage buttons. Gantz plays with the idea of "hey, what if they're just misunderstood," and then, for the most part, tosses that idea out of the window along with all possible ambiguous morality or subtlety. Gantz first dons a façade of depth via things such as cynicism and death, but it acknowledges this and subverts it over time as if its playing a joke on you. This is actually enjoyable if you have the right attitude and observe it like you would an Ed Wood film or something of that ilk. The amount of tropes it ultimately evokes may be record-setting, and this is, in a way, impressive in and of itself.
Terminated subplots are probably the biggest issue. At one point vampires are introduced. They are never explained, their exact abilities and motives are unclear, they just look like humans, and their whole diabolical vampire organization is forgotten. At one point psychics are introduced. Their abilities are never explained and the limits vary, the origin unclear. Things in this same vein happen again and again throughout the manga. That said, it's somehow a bit refreshing to have a poorly written series that just does not give a fuck about silly little things like "plot," if only in that it harbors no illusion as to its quality and just focuses on delivering good action and fanservice instead. The series is actually near-pure fanservice, in one way or another. At a certain point, if the plot gets bad enough, the author would be better off just not trying anymore. Gantz knows this. It knows where to focus its energy and how to play to its strengths. I wish manga like Bleach were more like that. Hilariously enough, the attitude the mangaka had while writing this manga epitomizes the nihilistic themes surrounding it far better than anything within the work itself.
Unfortunately, the action is marred by inconsistency. Really, the entire manga is, but I think we've established that. The way the weapons and suits work changes inexplicably from chapter to chapter. Hell, even the way Gantz beams people in varies, in more ways than one. Not to mention all of the rules and limits. As the combat lacks proper consistency, it consequently lacks proper tension. It can be pretty entertaining, like some cheap Hollywood popcorn blockbuster, but it doesn't offer much in the way of substance or emotion. Tension is further reduced as more plot points are introduced that make fatal injuries and even death negligible. There is the whole "what if the world is destroyed" thing, but the general populus in Gantz is so stupid that you kind of like it when they die.
The characters are all either one dimensional or they ended up having development that was completely contrary to everything we had learned about them previously. They sometimes work as semi-clunky plot devices, but they are hit or miss overall. Any development they experience is to serve the plot, contrived, and spontaneous. They all invoke the "parents do not exist" trope to some extent, because Oku considered the prospect of writing more characters and was all like "dude, fuck work" and then I imagine he smoked a joint or two and had a marathon Idolm@ster watching session with Kentaro Miura and Yoshihiro Togashi. That said, a lot of the characters do manage to be entertaining, and, due to the high body count, only a few of them overstay their welcome. The few that do, I want to stab, but I also get some kind of masochistic pleasure out of watching them succeed and I imagine Oku bestowed plot armor upon them for this very purpose.
The art is, surprise, surprise: inconsistent. Some faces are far too similar, or just generally not well drawn. Early on especially, they often looked really wonky. Landscapes are usually lackluster in terms of scope, and creativity during battle. I remember in a scene that took place in Italy the art was just chaotically beautiful, and repulsive simultaneously; the atmosphere was incredibly unique as well and I found myself wishing it was like that all the time, but alas, it was not. The different settings were usually not disparate enough, atmospherically. The aliens are mostly creative and detailed, with some exceptions, such as the entire final arc. The action is sometimes a bit hard to follow, but is generally fluid and well executed from panel to panel. The fanservice was generally alright, albeit forced as all hell, but I found myself thinking that Oku believes all titties are identical and are all the size of basketballs. I was gonna fly out to Nippon with my porno collection to teach a nigga about the vast spectrum of areolas and give him a tit diversity tolerance course and shit, but he eventually learned the concept of "DFC" and I was reasonably satisfied.
The rushed ending and drawn-out final arc is where Gantz went completely wrong. Expect to hear a lot of name-yelling by tragically separated lovers, expect the concentration of plot armor to reach unprecedented levels, expect one of the least subtle manga ever to get even less subtle, and expect to watch the only truly interesting character in the series turn into an annoying and generic Hollywood hero. Every single character morphed into a complete cliché, for that matter; even if they were somewhat cliché before, they still had some individuality. In the end, there isn't a single compelling character.
If you want answered questions, then this is not the place to go. The plot points that were resolved (most were not) were all resolved with a ridiculously random deus ex machina evoking the age-old maxims of "it was [more] aliens" and "don't read too much into it." The ending itself is not only a complete shift from everything that came before in the manga, it is completely devoid of all logic to an extent that I had never seen before this manga. Trust me, no exaggeration, wait until you read it.
If you want mindless—and I do mean mindless—action, then you're in luck, because that's all Gantz really delivers on. That said, it delivers on this somewhat well and with a sense of humor. It is actually at its best when it's overblown, unrealistic, exploitative, and absurd. If you go into it knowing what to expect then you should end up enjoying it somewhat. I have to admit, the only other manga this length that I have reread as many times is probably One Piece. The final arc and horrendous ending drag the final product down pretty significantly, but it's still not bad
I said "Hollywood" three times in this review, but don't get me wrong, it isn't really like any Hollywood film. There are just some similarities in the intent.