Why is it good?

Online IQ tests can satisfy curiosity about one’s cognitive abilities.
They offer a quick, informal way to engage with cognitive challenges.

Usually, they involve solving puzzles and brain teasers in online tests, which can provide mental exercise.

In educational contexts, teachers may use simplified IQ-like tests for fun or to engage students. But they can also be used as icebreakers in informal settings (e.g., social gatherings).

Some teachers think this is important because achieving a high score on IQ Tests can boost students' confidence and motivation.
 

Why is it bad?

Questions in IQ Test may not cover the full range of cognitive abilities, leading to skewed results.

They also attract self-selected participants, introducing sampling bias. People who take these tests may not represent the broader population.

Participants’ motivations (e.g., curiosity, boredom) differ from those in controlled testing environments.

IQ Test often lack evidence of validity and may not have high test-retest reliability due to inconsistent conditions.

Source:

Full Scale IQ Test (openpsychometrics.org)