Well, shitty isekai light novels tend to have really predictable storylines. They might have a set pattern where the MC just has to go on some basic quests, defeat some weak villains at first, and then suddenly become super strong. The world - building can be really lazy too, like just borrowing elements from other popular fantasy worlds without adding anything new. And the writing style can be very dull, not engaging the reader much.
Some are considered shitty because they lack originality. They recycle the same old ideas of a person being sent to another world over and over again. There's no fresh take on the concept.
One common feature is often a sense of disappointment. Since it's a bad end, the protagonist usually fails to achieve their main goals, like not being able to save the isekai world or themselves. Another feature could be the unexpected twists that lead to the bad end. For example, a character thought to be an ally turns out to be a foe at the crucial moment, which then sets off a chain of events leading to disaster.
Completed isekai light novels can vary widely. One feature is the creation of unique races and species. In 'DanMachi', there are all kinds of demi - humans and gods. The world - building is also crucial. In 'Konosuba', the world is filled with all sorts of wacky and dangerous creatures. The plot often has twists and turns. For instance, in 'Re:Zero', Subaru's ability to return by death leads to many unexpected developments in the story. And the way the protagonist adapts to the new world, whether it's through making friends, forming alliances or using their modern - world knowledge, is a common aspect.
The unique feature is the combination of modern weapon concepts (guns) with a fantasy isekai setting. It creates a contrast between the familiar and the otherworldly. For example, in 'GATE: Thus the JSDF Fought There!', the JSDF's guns are a huge advantage in a world of swords and magic. This can lead to interesting power dynamics and plot developments.
Often, they have unique magic systems. For example, in some isekai light novels, magic is based on chanting specific spells, while in others it depends on the user's mental power or a special ability they gain in the new world.
One common characteristic is the overuse of clichés. For example, the same old meet - cute scenarios like bumping into each other and instantly falling in love. Also, the characters are often one - dimensional, with the male lead being the overly handsome and brooding type and the female lead being the damsel in distress. Another aspect is the predictable plot. You can usually guess the ending from the very beginning, like they will overcome some minor misunderstandings and live happily ever after.
One unique feature is the protagonist being a slime. It's different from the common human or elf protagonists in other isekai novels. The slime form allows for some really creative abilities and story developments, like being able to absorb things and gain their powers.
Power progression is a common theme. The main character often starts weak in the new world but gradually becomes very powerful. For example, in 'That Time I Got Reincarnated as a Slime', the slime character gains various abilities and becomes a strong leader.
A common theme is starting over. The protagonist often gets a second chance at life in a different world. Another theme is power - up. They usually gain new abilities or powers in the isekai world. For example, in 'Sword Art Online', Kirito becomes a very powerful swordsman. Also, exploration is a theme. The characters explore the new and strange isekai world.
Another theme is adaptation. These characters are usually thrown into a completely different world with different cultures, magic systems, etc. So they have to adapt quickly to survive. Like in many isekai light novels, they may have to learn how to use magic or deal with strange creatures.