I wouldn't be humbled just yet, especially if you found some of the problems impossible rather than complicated but doable. A lot of people seem to have got unexpectedly low scores on this test. (And no-one's said 'Wow I usually do really badly on IQ tests but that one gave me a great score')

Go and read http://www.jperla.com/blog/post/how-to-ace-an-iq-test (don't look at the answers, just the methods) and then go back and redo the test. I imagine you'll then get a much higher score.

Then go and work out exactly what and why the answers on that test are as they are. (Perla has missed some of the explanations, but it's very satisfying to work out what the answers actually are. They're all perfectly logical and obvious-in-retrospect).

After that you should be reasonably confident that you'll do very well on any similar tests in future.

What that tells you about the nature of IQ tests and their calibration is debatable.