IQ is useful as a predictor of educational attainment as well as for detection of individuals with special needs in education and in other areas of social functioning. To my understanding, it is also generally accepted as a measurement of general intelligence in clinical practice.
There is robust evidence in that differnt aspects of cognitive performance in humans are positively correlated and the general intelligece theory states that this is caused by a common factor - the general intelligence which is supposedly approximated by IQ tests.
I can't understand the reactions provoked by this topic in some individuals. It seems to me that they're having trouble accepting that some people are more intelligent than others.
IQ does not mean everything for any human activity, including chess, and no professionals believe this is the case. It is true that many other skills are needed for any activity, and IQ may not be among the most important for most activities, but this does not invalidate IQ as a construct and its use in the situations I describe above.
The test given in this thread is of course a joke.
I got 6/10. I had the correct idea on no. 8 about perfect squares but was too lazy to work out which of the two 391 or 197 was not a perfect square. I also missed no.1, 4 and 7.