For a Computational Knowledge Engine” it's nearly worthless. The standard answer seems to be “Wolfram Alpha isn't sure what to do with your input'. Ask a question outside of the three that it's apparently programmed to answer, and that's it's response.
And ask as question that it's apparently able to answer – for example, input a stock ticker symbol, and you will get an answer.
In geologic time.
Tough to believe that somebody put out money to develop something as lame and over hyped as this.
And OBTW, Google returns some 368,000 results on the same search in about 0.22 seconds.
Somehow, I don't think that Wolfram has the Google crowd loosing any sleep.