These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Anticlimax Boss: Ginghamphatts in Samurai's Destiny, but only if you are really friendly with Magoichi. The latter will suddenly show up, talk you about his next goals and nonchalantly turn the big fellow to dust with a shot from his BFG.
Nobunaga's Golden Evil Statue form from Samurai's Destiny. While the previous form was quite challenging based on how he stays away from Jubei and performs multiple type of attacks, he barely tries to defend in the final round. The Unexpected Gameplay Change also made the battle much easier.
Breather Boss: Tenkai in Dawn of Dreams due to his simple attacks.
Complete Monster: Munenori from Dawn of Dreams. He attacked his own family, the Yagyu clan because he thought his grandfather killed his mother, which was his Start of Darkness. When Munenori's niece reveals that his mother actually gave her life to save him, and his grandfather had nothing to do with it, Munenori is initially taken aback. Then, he starts to laugh, and reveals he doesn't care what happened in his past, he will continue to be evil.
Mitsunari qualifies as well. Not only did he spearhead the Genma research that led to the creation of the Genma Trees and caused the entire country to be swept into chaos, he invited the demon Claudius to inhabit his body, willingly as opposed to being possessed, and as a result it became impossible to tell where one ended and the other began. Unlike Hideyoshi, whose grand delusions were stroked by the Genma Triumvirate, or Luis Frois, who began researching the Genma purely out of curiosity only to end up being possessed by Rosencratz, Mitsunari knew exactly what he was doing, and he wanted it to happen. It's enough to make one doubt he was ever human in the first place.
Demonic Spiders: Many Genma, except for the basic zombie grunt, are this, especially in Dawn of Dreams in the Demonic Realms, where you'll find lots of nasty Ninja, Giant Mooks and Invisible Monsters and no sense of Mook Chivalry. Airborne Mooks are particularly bad since most characters lack the appropriate means to deal with them.
Game Breaker: Dawn of Dreams introduces the ability to do chain attacks off level 1 magic attacks, rendering many other ways of starting a chain effectively pointless. This addition also makes level 2 and 3 magic far less useful by comparison.
However, Issen attacks dealt with a level 1 magic are less effective and grant you less red souls than a properly used Issen attack. Nonetheless, you'll still likely earn more than enough to upgrade your weapons and stats however.
Hype Backlash: While Demon Siege is praised for improving the gameplay and finishing the Nobunaga trilogy, producer Keiji Inafune himself noted that several fans were disappointed by how its story did not feel like a samurai tale which resulted in Dawn of Dreams removing its modern atmosphere.
Moral Event Horizon: Although she's highly unpleasant to begin with, Jujudormah crosses this when she slits Takajo's throat while Jubei watches.
Even though he was already a literal demon by the time it happened, it bears mentioning that Nobunaga actually did burn down the temples at Mt. Hiei in Real Life, so he qualifies for this both in the games and in the eyes of many historians. In fact, this act is one of the main reasons he receives a Historical Villain Upgrade anywhere he appears.
Ranmaru jumps the line when he kills little Henri for no reason.
Destroying the beautiful Mont Saint-Michel, along with all its imprsoned monks and pilgrims with your flying castle is bad enough, Vega Donna. But then you decide to use your BFG to wipe out the crumbling remains and any survivors? It's on.
Narm: The voice acting and dialogue. Oh, the voice acting and dialogue.
Scrappy Mechanic: The fixed camera sometimes makes it hard to notice the enemies.
The most common complaint the first two games got is the use of the dpad rather than the left analogue to move.
They Wasted a Perfectly Good Plot: Samanosuke's character in Demon Siege feels quite boring in comparison to Jacques'. He doesn't go through any sort of Character Development or thoughts about the past. For example, his rivalry with Nobunaga, relationship with the Oni, or his feelings regarding Kaede's fate are never explored. Instead, the plot focuses on more Henri's complicated relationship with Michelle while Samanosuke barely speaks.
Wangst: Even though Kotaro knows the truth about what happened to his mother, his denial caused him to hate every single woman and even try to kill Oyu. To be fair, he knew Oyu's true identity and believed she was an agent.
To be fair, Jacques was intentionally designed to look like him, just how Samonosuke was intentionally designed to look like his actor, Takeshi Kaneshiro.
Except they didn't let Jean Reno voice Jacques's English dialogue, which is over 90% of his dialogue. How awesome would it have been to hear Jean's smooth French accentented English while you're playing as him? The fact he's speaking his own French lines is weak compensation, even if they couldn't get him to do English voices due to time or money constraints.