Ironically, it's intellectually flawed.
It would've been good if it didn't do the one thing an I.Q test absolutely must not do in order to be accurate: Confuse intelligence with general knowledge.
The interface was solid, if a little bland. However, when you're trying to think about the questions it's actually better to have as few distractions as possible, so not overloading it with pretty backgrounds was probably the better option here. The same can be said for the music: It's not too intrusive, and the option to turn it off is a good idea in this case.
The major problem here was the content of some of the questions, most notably 8 and 13.
Question 8 is not an I.Q question for 2 reasons: First, if you don't know what the English spelling of the country is in the first place (and there are at least 5 different spellings for it just using normal European letters), you aren't going to get this right through any means other than random chance. Either you know it or you don't. Secondly; with the millions of towns in existence on Earth, the chances of those letters being arranged into a town name by accident is quite high.
Either way; your ability to answer Q.8 has little to do with the internationally recognised definition of 'intelligence', which literally reads:
"The speed at which one adapts to unfamiliar situations."
Since it's impossible to "adapt" your thought patterns to answer a question that relies on background knowledge, it's not a valid I.Q problem.
To that effect, 9 and 10 have the same problem since they can't be worked out from the wording of the questions either: you either know the meanings of the words or you don't. As simple as they seem to you and me, it can't be assumed that everyone knows these things. What about all the people who aren't native English speakers and / or have skewed knowledge of the language?
Then there's 13. Again, the same problem. My education never focused on the meanings of any of those words, and I'm a native English speaker. Does that make me innately dumber than someone who's been given a slightly different education? I hope not. Intelligence was supposed to be independant of education anyway.
I'm sure you get the idea by now, so let's just say 15 was the same thing, for the same reasons stated already.
To conclude: A good first attempt as far as the interface and programming was concerned, but wherever you got these questions from is not a reliable source of IQ problems, making for an invalid test overall.
(P.S: 136. No, I'm not writing all this out of butthurt over a low score either. :P )