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: Super Mario Bros. 2
Base Breaker: The third world's dungeon is seen by some as a huge difficulty spike due to the shy guy pots and lots of spark platforms and increased length, while others see it as the easiest dungeon in the game due to the abundance of POW blocks, the near absence of instant death traps, the ease of escaping the Phanto, the fact you get all your hearts early, and the lack of Zerg Rush enemies in the dungeon.
Demonic Spiders: Bob-Ombs, when uprooted, often have an extremely short fuse, damaging you if you don't throw them in time.
Difficulty Spike: Depending on whether or not 3-3 is difficult for you or not, this either happens there or in 4-2, a level with a very hard to find fourth mushroom, Zerg Rush beezos BEFORE you get to the third mushroom, and some annoying platforming involving an autobomb, not to mention fighting Birdo on ice. The difficulty spikes again in 5-3 with an area overflowing with enemies plus a tough climb up inside a tree. Then you have to fight Clawgrip.
Fan Dumb: Gamers can't agree on whether The Lost Levels or the North American version of Super Mario Bros. 2 is the true sequel. Let's just leave it at that.
Fanon Discontinuity: Some fans refuse to accept the game as a part of the Mario series and refer to the Lost Levels version whenever they bring up Mario 2.
Peach's hovering ability. Don't have to worry about risky jumps jumping on disappearing logs when you her ability to jump and just levitate over them.
In general; Luigi breaks vertical jumping, Peach breaks horizontal jumping. (Mario's vertical jump height is actually better than Peach's.)
Interestingly enough, the game manual declared Toad this, due to his speed and power, saying that you will use him the most, with Luigi and Peach only for levels that require their jumping abilities.
The Game Boy Advanceremake made shells rebound from walls instead of disappearing upon contact, and it now always generates hearts for every enemy it kills, making it ripe for exploitpotential.
Giant Shy Guys and Ninjis, who drop hearts when thrown, making them an easy source of hearts should you find yourself taking too much damage.
Hate Dumb: This game has a small hatedom that showed up merely because of how different it is from other Mario games. At the time, we didn't know—and even on its own merits, it's still pretty well designed. There are some people who like it because it's different from the other Mario games that feature more linear levels. (While not really "non-linear", they aren't "go to the end of the screen" like in the first Mario game.) Heck, if you think about it, Doki Doki Panicwas going to remain Japan-exclusive, so reskinning it as a Super Mario Bros. title actually kept it from becoming a cult-classic known only to emulators.
Not to mention, The Irate Gamer review of this is pretty much a good example of Hate Dumb - even if he does bring up one or two valid points such as how utterly chaotic the game gets and the fact that it's not easy (Unless you have a save feature that enables you to practice on later levels)