Designing the Zoombinis in your groups to be as similar as possible will make puzzles based on their features significantly simpler. In some cases (particularly with Captain Cajun's Ferryboat), it can become literally impossible to mess up.
In the original version of Logical Journey, you can have groups where every Zoombini had a twin, halving the difficulty of nearly all feature-based puzzles. The Fleens do become harder to deal with since you may have to guess the right one twice, but you can avoid them by taking the northern route. Not possible in the remake, since you can't have twins in the same group any more.
In the remake, you can close the game in the middle of a puzzle, which will reset when you open the game the next time, eliminating the need to start the whole leg of the journey over if you screw up.
Genius Bonus: For a children's game, it teaches surprisingly deep lessons on logic, set theory, and linear algebra. (If you aren't guessing randomly, that is.)
It's Short, So It Sucks!: A complaint several people have about the remake is that saving only 400 Zoombinis is required for the game to consider it 100% Completion rather than one for every possible feature combination, equaling 625note Usage of twins meant some combinations would go unused. like the original.
"FLEENS? You're not Fleens! Whatever you are... MAKE ME A PIZZA!"
The narrator's hammy line "Hip hip, ZOOMBIIIIIINIIIIIII! Hip hip, ZOOMBIIIIIINIIIIIII!"
Nightmare Fuel: The very premise of this game is horrifying. The main characters are horrendous.
Much of the game, due to the eerie music and often surreal visuals, but especially the final leg through the mountain caves.
The Lion's Lair lets you throw Zoombinis into the abyss. Sure, they get chucked back, but still...
Bubblewonder Abyss is especially worst. It has a dark atmosphere, creepy sound effects in the background, and the ability to vaporize any Zoombinis who take the wrong path through the maze (like the Lion's Lair, you get them back, but that didn't make it any less scary!).
Recycled Script: The two TLC games have various puzzles that are obvious retreads. Jarringly, there's even a retread of Pizza Pass in Mountain Rescue featuring new creatures called the Norfs.
Surprise Difficulty: The game's design appeals to kids, but the Very, Very Hard difficulty is notorious for being a true challenge even for adults; Hotel Dimensia and Lion's Lair has made people tear their hair out.
That One Level: Pretty much everything on Very, Very Hard. Hotel Dimensia and The Lion's Lair deserve special mention. The hotel has literally 125 rooms, meaning it's Trial-and-Error Gameplay here more than ever. And there's no clock to gauge how many chances you have left. If you can't figure out where each one goes in the time allotted, then too bad. As for The Lion's Lair... in this level, you'd get some sort of hint as to how to properly order the Zoombinis. Your hint here? You don't get one. This basically makes it like Hotel Dimensia with less chances to screw up; after your sixth wrong placement, the gate slams down and you can't take anybody else through.
Hotel Dimensia on Very Hard is worse. A number of the 25 rooms are boarded upnote Sometimes mistaken to be random, but the boarded rooms are another hint; they mark Zoombini combinations that aren't in your party., meaning that if you place the first Zoombini in the wrong room, you've just irreversably screwed any chance you had of continuing with a full team without knowing it. At least on Very, Very Hard you can place a Zoombini in the right room without it being boarded up, even if there are 125 different rooms.