As noted previously, I recently watched the 2005 Guyver anime.
As noted previously (yes, I realize I'm repeating myself), Guyver pays homage to the older tokusatsu programs, particularly the original Kamen Rider, which it is very like while going in different directions permitted by its different media (manga and anime as opposed to low-budget live action). Its direction is also different because the scope is deliberately rather larger-while the original Kamen Rider is the battle between a neo-Nazi organization called Shocker and several of their rebellious creations called Kamen Riders, it turns out that Chronos, the less Nazi-esque organization that is linked to the Guyvers, created less and is working off of leftover material from an alien civilization that created all life on Earth.
Yeah, it's one of those series.
Guyver is dark, bloody, features non-explicit nudity (slightly more explicit are largely unnecessary shots of several dudes' butts at various times, because generally the villains explode out of their clothing when they transform-the Guyvers don't have this problem, but there are still circumstances under which they lose their clothing, which I'll talk about in a bit), and quite a bit of swearing.
However, it never really feels gratuitous, despite the violence often being rather extreme. For that matter, the swearing never feels out of place (and that's a problem a lot of series have).
Things are pretty violent from an early point (the first episode features Guyver I, within seconds of his first transformation, casually ripping off the arms of a massive, monstrous opponent who had earlier shrugged off a grenade and then breaking his neck), but the tone is really set by the end of the sixth episode, "Beyond the Desperate Battle," when a new enemy type uses a suicide attack to outright melt Guyver I into a puddle. And then Guyver I gets better (and since his clothes were melted, he's naked, as noted above-my sister laughed so hard). Better yet, on multiple occasions, Guyver I wanders around killing people while he's technically unconscious, and is a better fighter when he ought to be clinically dead than when he's in good health. ...It makes sense in context.
As for the swearing, it's fairly frequent, but when you consider that these people are being confronted by some truly insane events, who wouldn't swear like that in their positions? ("Oh, I've got the Guyver on the ropes, and he doesn't stand a chance! Wait, he just grew swords out of his arms and started dismembering me? [EXPLETIVE] what the [EXPLETIVE] [EXPLETIVE] [EXPLETIVE]?!!??" "Oh, Guyver I is dead, and Guyver III has infiltrated the base. Oh wait, Guyver I is alive and inside our base because we took a sample, and Guyver III apparently has intimate knowledge of our facilities? Wasn't Guyver I turned into a [EXPLETIVE] puddle? And now he's killed a guy who was specially designed from data on his fighting abilities to fight him? And OH [EXPLETIVE] THEY'RE HERE [EXPLETIVE] [EXPLETIVE]-Ghk!")
Narratively, there's a small problem I have with the story generally, that being that after a certain point, the villains just start walking all over the protagonists, and this trend doesn't reverse until the end of the final episode, which takes place after a year-long timeskip which sees Chronos conquering the entire planet. (The series ends on an odd note, that being that Guyver I has just unveiled his awesome new game-changing powers and come back after a year of seemingly being dead, but the series producers were probably hoping for a third season, the Guyver manga is still ongoing, and it's actually a surprisingly satisfying end of the story arc, even if there are literally dozens of loose plot threads.)
Outside of the story itself, there's another problem: The Guyvers are genuinely among the most powerful anime/manga protagonists (well, the non-planet-busting kind, anyway), but they tend to misuse their powers a lot.
(WARNING: About to get seriously rambly.)
Not as badly as in some other series, but there are still some clear flaws. The poster child for this is the Guyver's head beam, which in the second episode, its debut appearance, is used to stop a bullet from hitting Guyver I's buddy.
He starts using it a lot less by the fourth or fifth episode because it never seems to actually work on most enemies after the first few-the third episode featured an enemy who got shot through the chest with it, but merely regenerated from it almost instantaneously. So perhaps he has forgotten the original usage when he encounters multiple enemies who fire guided missiles that are considerably larger and slower (and thus much easier targets) than bullets. You've got frikkin' point defense, and these are bothering you at all? (Granted, said enemies have lots of missiles they fire all at once, but the beam is actually a continuous beam that can be used to cut things in this particular series.)
Not much better is the gratuitous misuse of the mega smasher. The mega smasher is described as the strongest weapon the Guyvers possess, and in terms of raw brute power, that's pretty much indisputable. Its destructive potential is so great that it's only used in isolated areas, because otherwise they'd be knocking down buildings and wiping out whole city blocks. It also has rather long warmup and cooldown times, leaves its wielders with an opening in their armor, and also has a telegraphing glow it emits. (It's also rather inexplicably stopped by clever use of vibrating blades, which since it's some kind of "particle beam," makes about as much sense as stopping a flamethrower with a wiggling sheet of paper.) The mega smasher also requires full use of one's arms, as a Guyver must manually pull open the armor plates covering it. (This is mitigated a bit by the fact that the smasher can be fired one-armed at half strength.)
As a result, it's the likeliest weapon in the entire series to fail spectacularly. Guyver III, the second heroic Guyver, seems particularly vulnerable to this-while Guyver I fails on multiple occasions, it's justified at least partly by the fact that he's actually a terrible strategist. Guyver III outsmarts numerous individuals and has considerable combat training intended to bring out the potential of a being like a Guyver. And so what happens when he tries to use his mega smasher? He epic fails almost every time. Taking a guided missile to the chest while charging up, for instance, or failing because the enemy is spectacularly stronger than he expected (and for that matter almost invincible even compared to a Guyver), or because the enemy did something that was a stretch by any standards (see above about the vibrating blade thing).
You'd think that Guvyer III at least would have learned to charge up the mega smasher while the other guy didn't even know he was in a fight yet, then jump out and fire it. But no, the closest anybody ever gets to that is Guyver I charging his mega smasher while it's closed (which is odd that it's even possible, and odder still that they'd not do it this way normally) and then popping it open by sheer force of will (instead of using his arms) and firing immediately. (Incidentally, that's easily among Guyver I's most awe-inspiring moments.)
Possibly the single worst misuse of powers, though, is the "sonic emitter" weapon.
When it debuts, it's something of a deus ex machina to get Guyver I out of a fight with enemies with sonic powers. It overwhelms these enemies' own sonic powers, which cancelled out all sound to the point where the sequence seemed unreal (this was part of the point of the ability). It turns out to be pretty powerful, able to completely destroy enemies without harming the surrounding area-in fact seemingly being able at fully strength to destroy enemies as quickly and totally as the mega smasher without the collateral damage-thus being possibly the Guyver's most useful weapon.
And after that, it's used maybe two or three times... and that's it.
Seriously, you forgot that you have a weapon that can destroy your enemies effectively without the long recharge time and high collateral damage of the mega smasher?
(MASSIVE RAMBLY WARNING OVER.)
Regardless of all that, it's a pretty good series, and since you can watch the whole thing on Hulu (provided you're an adult with a Facebook or Hulu account), I pretty much have to recommend it if you don't mind the things I'm talking about (and even if you do somewhat).