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: No More Heroes
Best Boss Ever: Henry. We're talking about a Duel Boss with an outrageous amount of health on Bitter who is extremely deft with a blade and has what is perhaps the most awesome One-Hit KillMeteor Moveever. And to top it off, the stellar Boss Remix known as "We Are Finally Cowboys" is blaring in the background. He's also the pinnacle of "Real Difficulty" in the game. Your standard dodge-and-counter tactics will work, but it will take forever. His attacks are telegraphed just enough to be fair, depending on how much damage they do. He can be dizzied, but it takes a suitably large number of consecutive hits to do it, but he also offers very small windows for guard breaks. And of course, he can take close to a thousand hits, not counting any wrestling moves you land on him. A Marathon Boss if there ever was one.
No More Heroes and the sequel are well known for having fantastic boss fights (with a few exceptions.) Bad Girl is also a frequently cited favorite.
Travis' dream on the train to the Rank 4 fight. On the other hand, it is a fun little Bullet Hell minigame, even if it has no logical reason to exist.
Travis is a huge game and anime freak and he has that video game at home. Clearly he's just experiencing The Tetris Effect.
Breather Level: Letz Shake. Destroyman, despite being a fan favorite, is a fairly easy boss to take care of and his stage is nothing special either. And it comes right in between Shinobu and Holly, considered two of the harder bosses in the game.
Ear Worm: The main No More Heroes jingle wont ever get out of your head. Ever. Bad Girl's theme, "Pleather for Breakfast," also counts. The lyrics are indecipherable, but the song's very earworm-y.
Or, how about that stupid buzzing before you fight the boss in the Pure White Giant Glastonbury dream sequence. Or that squeely whining in the beginning of "Vioectrolysis", the music from Harvey Volodarskii's fight.
Ensemble Darkhorse: Henry is a parody of this trope. It still didn't stop him from actually becoming one to the point of becoming playable in the sequel, although only for one boss battle.
Destroyman proved to be one of the more popular assassins in the first game due to his memorable boss battle and Large Ham tendencies, even if he was basically a Breather Boss. He got enough of a reception to get brought back in the sequel.
Bad Girl inspite, or possibly because of how Ax-Crazy she is, and her memorable theme song.
Everyone Is Jesus in Purgatory: From the standard "is the hero imagining the whole thing" to fairly interesting examinations of the way the game links sex and violence, particularly in Travis' interactions with female opponents.
Freud Was Right: The way Travis charges his sword looks like he's jerking it off. It gets worse in the sequel when the icon for the beam sword's power meter turned out to look like a dildo...
...If by "dildo" you mean "a wang with a face that is proportionally longer, more erect and happier the more charge you have in your sword", then yes.
Speed Buster's weapon is very long and BIG. Speed Buster's stage is very long. The laser that comes out of Speed Buster's cannon is HUGE. And if you try to attack Speed Buster without damaging her weapon, this boss can easily become hard. It's like the entire level was designed to secretly joke about someone with a huge penis.
"Funny Aneurysm" Moment: The first game has Bishop's ex-girlfriend texting him once in a while to tell him to go die. Guess what happens in the sequel...
Germans Love David Hasselhoff: The original game bombed in Japan but was a huge hit in the U.S., which is why the sequel was released there first.
Harsher in Hindsight: The Pizza Butt missions become a lot harsher once you discover the consequences in the sequel.
Holly Summers' suicide as well carries more weight after seeing Ryuji's fate.
Misaimed Fandom: Believe it or not, there are many fans who revere Travis and aspire to be like him. You know, despite him being a loser otaku who spends all of his money (which he earns mostly from killing people) on anime stuff rather than move out of a hotel room. Suda 51 must be laughing his ass off at that.
Most Annoying Sound: The mook's quotes quickly become this. There's only so many times you can hear MY SPLEEN!!! before it starts to get REALLY annoying. (Gettin' yer jollies?)
Most Wonderful Sound: Travis' beam sword, as well as Henry's. Your ears will have an orgasm during the fight against Henry at the end of the game.
One-Scene Wonder: Technically speaking, most of the Assassins. The match is set up, they appear out of nowhere, some character development here and there, boss battle, then BOOM! Dead and gone. A few of them get a rather touching sendoff. This is grimly noted in the sequel.
That One Boss: Bad Girl is guaranteed to kill you at least once unless you already know that she's going to pull a Wounded Gazelle Gambit (and even then, just getting close enough to check to make sure she's not holding back will probably get you killed anyway). Then she's... still very hard, having great damage output, health and mobility.
Shinobu is one of the more reviled bosses, especially on Bitter. She's extremely dodgy and evasive, she'll outright make you lose every weapon clash, and she has that damn Gengoken (nearly instant-kill) and multi-shot Sonic Sword that will make you beg for mercy. Doing nothing but low charged attacks and some occasional sword swipes can make the fight easier, though.
Holly Summers. Take Shinobu's speed, add a tendency to run away whenever you get close, pits all over her arena that will interrupt your game flow and wear out your thumb, and unblockable butt rockets that seem to hit at least 50% of the time assuming your timing's average. Which she loves to spam. It may get to the point where you're purposefully falling into the pits just to dodge the rockets, because it's easier to dodge the grenade she throws into the pits, but that'll also give her plenty of time