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.
YMMV: Disgaea Dimension 2
Awesome Music: Dramatic Devil Story is fittingly epic for the battle with Xenolith.
Broken Base: The return of the Weapon Mastery System. As mentioned on the main YMMV page, some fans were glad to see it go when Disgaea 3 came out while others weren't as enthusiastic. While being able to tweak the Weapon Mastery rate with the Cheat Shop and some other changes help alleviate some of the backlash, the base is still divided on which of the two methods of gaining skills was better.
The Monster Mounting replacing Magichange. Those who prefer Monster Mounting like that it allows monsters to ferry the humanoid characters, act as a mobile meat shield for weaker characters early in the game, and is not limited by a turn limit. Those who prefer Magichange don't like that humanoids are limited to magic skills while mounting, that the overall uniqueness and stat boosts from Magichange outweigh the turn limit, and that while mounting looks perfectly fine for larger monsters like dragons, it ends up looking silly on the more humanoid looking monster-types like Raspberyl and Metallica.
Character Rerailment: The main cast has been hit hard by Flanderization in their guest appearances over the years since the first game, which at first glance seems to have stuck as of the beginning of this game. In truth, it's more a case of Jerkass Fašade and Vitriolic Best Buds than anything, and the character development did stick (and in fact gets expounded on), it's just not obvious from their day-to-day interactions.
Fridge Logic: According to the artbook, Sicily is 937; nearly 400 years younger than Laharl. Are we seriously expected to believe their human mother lived for that long after she had Laharl?
Salvatore because her evility. It performs one of several randomly selected buffs to adjacent allies, but when the options are increasing movement by 10, range of attacks and spells by 9, jump by 99, doubling damage dealt, and cutting damage taken down to 10 percent of normal, you can't really complain.
Pram's evility includes poison (that always hits), a hit on a ramdom enemy, a free 50% INT boost for all allies, a 100% Attack boost for herself and 50% evasion for all units.
That One Boss: So, thought Baal in Disgaea 4 was too easy? Apparently, so did Nippon Ichi, because they took that and made him even harder. He can only be fought in Raesetsu Mode, so his stats are going to be stupidly high (five-hundred million at the very least), his items can't be stolen, he doesn't lose his stationary bonus (normally, stationary bonus adds extra power each time a unit attacks without moving), has Ultimate Force from Disgaea 4 (the evility in which one of his swords drops on your character the moment it's summoned from the base panel), and a variation of Pringer X's Super Skill Solved evility (specials from a single character cannot be used more than once). Bring him down, and it turns out he has a new form and with it a new evility and will do this five more times. New evilities include inflicting all status effects, increased evasion, summoning mini-Baals, automatic damage at the end of turn, and base panel destruction. Good luck.
What an Idiot: Barbara doesn't try to win her first fight with Laharl because she wasn't ordered to and in one of the bad endings, doesn't run for her life when a black hole forms because she wasn't ordered to.