So Wolfram Alpha - much talked about Google killer - is out. It's not really a Google killer - it's more like an oversexed version of the Google Calculator - good to deal with a curated set of questions.
The cooked examples on the site often look great of course, there's stuff you would expect from Mathematica - maths and some physics, but my first hour or two with the service yielded very few answers corresponding to the tasks I set my self.
I figured that one of the strengths in the system was that it has data not pages, so I started asking for population growth by country - did not work. Looking up GDP Denmark historical works but presents meaningless statistics - like a bad college student with a calculator, averaging stuff that should not be averaged. A GDP time series is a growth curve. Mean is meaningless.
Google needs an extra click to get there - but the end result is better.
I tried life expectancy, again I could only compare a few countries - and again, statistics I didn't ask for dominate.

Let's do a head to head, by doing some stuff Google Calculator was built for - unit conversion. 4 feet in meters helpfully over shares and gives me the answer in "rack units" as well. Change the scale to 400 feet and you get the answer in multiples of Noah's Ark (!) + a small compendium of facts from your physics compendium...

OK - enough with the time series and calculator stuff, let's try for just one number lookup: Rain in Sahara. Sadly Wolfram has made a decision: Rain and Sahara are both movie titles, so this must be about movies. Let's compare with Google. This is one of those cases where people would look at the Google answer and conclude we need a real database. The Google page gives a relief organisation that uses "rain in sahara" poetically, to mean relief - and a Swiss rockband - but as we saw Wolfram sadly concluded that Rain + Sahara are movies, so no database help there.
I try to correct my search strategy to how much rain in sahara which fails hilariously by informing me that no, the movie "Rain" is not part of the movie Sahara. Same approach on Google works well.

I begin to see the problem. Wolfram Alpha seems locked in a genius trap, supposing that we are looking for The Answer and that there is one, and that the problem at hand is to deliver The Answer and nothing else. That model of knowledge is just wrong, as the Sahara case demonstrates.
The over sharing (length in Noah's Ark units) when The Answer is at hand doesn't help either, even if it is good nerdy entertainment.

Final task: major cities in Denmark. The answer: We don't know The Answer for that - we have "some answers" but not The Answer, so we're not going to tell you anything at all.

Very few questions are really formulas to compute an answer. And that's what Wolfram Alpha is: A calculator of Answers.