Well there are a number of problems with IQ as a measure of intelligence.
Probably the most serious problem is that there is no accepted definition of intelligence. Thus IQ tests often turn out to be measures of a person's puzzle solving ability rather than the person's intelligence(This also means that if a person practices on a large number of puzzles for a certain amount of time, his intelligence would go up dramatically!)
There is a second problem with IQ. IQ tests often involve a test of linguistic ability and this is a serious issue. It is natural that a person with English as a second language would not be very proficient in it. This however has no relation to his intelligence.
The Linguistic part of IQ tests was in fact used(in the early days of IQ) as a means of racial discrimination...
I dont know how important all of this is today, because IQ has lost its importance(and thus even its utility in racial discrimination). Of course there is Mensa and some people might even use to word IQ to mean intelligence but that is just about it...