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.
The suits of armor in the ghost house in Spookane hit like a freight train compared to the other enemies found there, and take far longer to kill.
Disappointing Last Level: Honestly, you could rename the trope Mt. Itoi Syndrome and get the same effect. The beta testers ran out of time and the only way to get to the final boss is hours of tedious, dangerous grind.
Epileptic Trees: Like its successors, a magnet for these, especially concerning Giygas. The backstory is more implied than spelled out, leaving plenty of room for interpretation. Same thing with most of the setting, like Duncan's Factory.
Goddamned Bats: Plenty of these, too, especially since you can't skip low-level encounters like you can in the sequels.
Heartwarming/Hilarious in Hindsight: Shigesato Itoi was known to smoke a lot. The Crow smoked in the original release, but after the unreleased English version Bowdlerized that, the change was also in MOTHER 1+2. Near the time MOTHER 1+2 was released, Itoi quit smoking.
It's Hard, so It Sucks: The heavy grinding and less forgiving dungeon design common to early rpg's is the main thing that tends to turn even hardcore Mother fans off from playing it. To the point when Tomato finished his Fan Translation of the game, he hacked in the Easy Ring which increases experience gained and decreases enemy encounter rates, literally the first item available in the game to help new players.
Jerkass Woobie: Giygas loved Maria very much, but was forced to lead the Earth invasion by his people for vengeance on George for stealing their PSI information. He killed her in attempt to get rid of his deep feelings of love for her, but that doesn't work.
Narm Charm: The official licensed English album is well-composed and produced, especially for it's time. The lyrics however, can be seen as cheesy and overly peppy, particularly the rendition of "Pollyanna". Performing at the age of 14, Catherine Warwick's delivery is rendered slightly incomprehensible by the production with a noticeable accent. And yet, she sings with utter conviction and sincerity, capturing the childlike innocence like nothing else could have, and is precisely why it's considered the definitive theme of the series.
Player Punch: Giygas begs you repeatedly to stop when you fight him and start singing the Lullaby.
Polished Port: The MOTHER 1+ part of MOTHER 1+2 is much more accurate of a port (and even received some updates) than the lower-quality MOTHER 2 side of it was. Despite this, it was MOTHER 2 that was the focus of the game's commercials.
Scrappy Mechanic: The battle system may be the sole reason why this game is less popular than its sequels outside of Japan, as it's just a bad Dragon Quest clone in terms of gameplay. (Remember that the reason Itoi decided to make a video game in the first place is because he played Dragon Quest, so the similarity is inevitable.)
The fact that random NPCs can give Ninten a cold, which acts like poison and can only be gotten rid of by a trip to the doctor or some Mouthwash (which you can't buy until you reach Snowman.)
Sequel Displacement: Despite being the first Mother game, it's the most obscure. Notice how Ness, Lucas, Porky, and various references to their games are in the Super Smash Bros. series, but all this game gets is some music (most of which are used in all three games, or at least EarthBound) and a few stickers in Brawl. Oddly enough thought, it's Mother's version of Magicant that appears as a stage in the fourth game rather than Earthbound's.
That One Boss: The game has only a handful of bosses, but the Dragon in Magicant stands out for his powerful normal attacks and devastating PSI. Even with a PSI-Block from Ana, it's still a very challenging fight.
Woolseyism: Many of the (Itoi-approved) changes Nintendo of America made in the unreleased American version, including the run button and an epilogue, were added to the game in Mother 1+2, a GBA port of this game and EarthBound.