Primarily Revenvengeance is just another swordplay action game. Granted, it combines the familiar gameplay mechanic to a series mostly known for stealth and crazy plots. The latter is of course intact in Revengeance as the plot makes very little sense at any point. As a game it follows most of the tropes in its genre, including the bad ones.
1. The camera problem
Indeed the biggest issue I had with this game was its camera and honestly I cannot recall a fast-paced action game where camera would not have been an issue. In slower games like the Souls series camera works just fine most of the time (some bosses in at least Dark Souls made the camera go batshit though). I do find it curious that developers insist on making games with very fast-moving enemies while keeping the camera very close to the protagonist's back. If the enemies move slow enough, there is no issue because they cannot suddenly strike from far beyond vision range. Fast-moving enemies also make all kinds of locking systems a pain, because once you lock onto one, it's going to get rather nauseating.
The camera issue is quite simple: in real life, when fighting with melee weapons, people are perfectly able to glance quickly at their sides/behind to see what is going on there. So far there has been no viable way to do this in games. The thumbstick, your friendly neighborhood camera controller, cannot do both accurate and fast. If the sensitivity is fast enough to allow quick glances, you can bet it won't be accurate enough for anything else. It is also far more disorienting to do quick perspective changes in games because the player lacks body sense in the situation. The situation is worst in first person action games, which I think I discussed in my analysis of Dishonored. Moving the camera behind the player's avatar does, in a way, simulate peripheral vision and also the ability for quick glances by showing what is going on the sides.
The situation is somewhat remedied by game mechanics in some games. Devil May Cry has fixed camera angles but experts find it quite playable because of two features: one, all enemies make a sound before attacking; two, jumps and dodges have invincibility frames at the beginning. This means that even attacks from out-of-view enemies can be dodged at all times if the player is careful enough. The system in Revengeance is a bit problematic in this regard because its primary defensive system is parrying and the player is required to press the left thumbstick in the direction of the attack and time the parry correctly. The game assists in this by highlighting when enemies are about to strike, but this is of little help if they are out of view. For this reason Revengeance is somewhat more infuriating with its camera problems than most games in the genre.
One way to deal with camera issues I believe Revengeance should have taken would be to move the camera further. The downside of this of course is that as enemies become smaller, they attacks are harder to discern. However, the game already uses rather blatant highligths and discerning those should not be a problem. Unless it is a technical limitation, I don't think there is any acceptable reason for the camera being so close - especially if they are unwilling to make enemies jump around a lot less. In summary: close camera + fast enemies is a bad combination, but especially so when the primary defense mechanism relies on the player being able to discern each attack's direction. It gets even worse near walls, because the camera does sudden resets (instead of, say, making the walls invisible when they would obstruct the view).
Although the camera problem is rather ubiquitous in this genre, that doesn't mean it should be accepted. Here's why: bad usability is a shitty way to make a game challenging. I highly doubt that Platinum Games wanted to make camera control into a central mechanic in Revengeance - and since it's not part of the core gameplay, it should not get in the way. Some people have excused things like bad controls in Silent Hill because they somehow add to the game's feeling of helplessness. I say we should stop excusing things like this - there are other ways that don't rely on frustrating the player.
2. Feedback matters
If you have not read it yet, this article does a lot to explain Revengeance's appeal. In short, the violence itself is not the source of the appeal. The violence is just a graphical metaphor for the truly appealing force: feedback. The messy headshot is a very clear indicator that you did well. Revengeance pretty much takes this to the extreme. It is indeed hyper-violent, but not for the sake of violence. The most violent stuff happens in cutting mode, where the player is allowed to literally cut stuff to pieces with rapid slashes. This mode can be used to instantly kill any normal enemies. Furthermore, if you make a cut in the right angle and hit the enemy's power core, Raiden will grab it from the splitting body and instantly refill his health and the energy meter you need to do these cuts. That right there is a very powerful indicator of success - a positive feedback loop even.
So the game reinforces your behavior of scoring instant kills not just with a cool visual effect which in itself is rather satisfactory - it also gives you the power to do more instant kills quicker. Perfect parries are similarly rewarded: you get a cool effect, your meter refills and you get an instant kill option right there. Overall, anything that the player does "right" gives satisfying visual effects in the least, and often gameplay rewards that enable the player to do even more cool stuff. Other important things like stagger have been well implemented. All this makes the game a very satisfying experience. The over-the-top attitude shows not just in cheesy cutscenes, but all over the gameplay. Lesser action games could learn a lot from Revengeance. Platinum Games definitely have a knack for making the player feel empowered when they succeed.
Dante's Inferno is one example of a game that could learn a lot. I'd also throw God of War to the lot, although I'm risking a lot of flak doing so. The games share a lot of genes. Most importantly, battles in both of these games feel very stagnant compared to Revengeance. It just feels a lot more like attrition where the player slowly chips life away from enemies. The weird thing is, these games share most of the mechanics with Revengeance. They just do so in a manner that is several magnitudes less satisfying. They have instakills, and they reward instakills too, but the oomph factor is severely lacking. One key difference is pace. Revengeance is wicked fast. The player hits hard, as do the enemies. Enemies fall left and right, often in mere seconds. It feels like the game is constantly moving forward whereas Dante's Inferno in particular feels like you are forever stuck in every single fight.
Revengeance - even with its flaws - is definitely one of the better games in its genre. It's up there in the company of Devil May Cry (original series) and Ninja Gaiden. It doesn't have any revolutionary mechanics. Rather it just does the basic gameplay in a manner that totally reinforces good play. Although I did compare it to God of War, the games are actually in slightly different categories in my opinion. God of War is more oriented towards casual audiences who might not be as interested in mastering every technique in a game. The difference is quite subtle because on the surface these games feel very similar. Revengeance is purely devoted to one thing: fighting enemies with style, whereas games like God of War throw in a fair bit of exploration and trivial puzzles for a more varied experience. Revengeance is much more suitable for the DMC/NG crowd.