My biggest problem with IQ testing is an unacceptably high number of "false negatives." That is to say, I am not arguing that people whom the test identify as 'smart' are not actually smart (false positives), but that many people who fail the test are actually smart, but not good test takers (or at lest not good takers of the tests in that particular format.).
I would also add that these who fail standardized tests are often the most creative and intelligent people (cf. Einstein) so using these instrument for "gate keeping" as many colleges do does a profound disservice not just to these individuals but to the society as a whole.
Wojtek