If anyone comes out with a website that purports to provide quick access to information, it'll inevitably be compared to Google (or Yahoo, or Live Search, or whatever comes next). Slate's comparison is actually even pretty close; the author took the examples provided and tweaked them slightly.
For example, "running 4mph 30 minutes 5'10" 160 lbs 40 year male" provides an answer, but "golfing 4mph 30 minutes 5'10" 160 lbs 40 year male" doesn't. I think that his conclusion was the most interesting part, about "the eternal problem for any wannabe Google competitor[: ...] Google can easily co-opt such improvements -- and suddenly everyone's got a better Google."
Out of curiosity I tried seeing the the calories burnt were any different for a 60 year-old man or 9000 year-old man. Apparently, they aren't.
http://www28.wolframalpha.com/input/?i=running+4mph+30+minut...
NB: we're still talking about it: the message will reach everyone who might need it, with zilch advertising budget.
BTW: much as I agree it's not a search engine, I just added it as a search engine to FF, for convenience: https://addons.mozilla.org/en-US/firefox/search?q=wolfram (I got the middle one, by phoque)
And you'd have to be a fanboy or an idiot to NOT compare Google to W|A. They both do the same thing, only W|A doesn't do it very well. I know since I've used them both.
They both have a text box where you can enter stuff, and it will return some results. The stuff you're supposed to enter, and the results they return, though, are entirely different.
--Conrad Wolfram
"look like a normal search engine" - translation 'it's like google'
"Change the way people search online" - translation 'it's better than google'
The biggest problem for WA is that it is different enough that people used to the Google way of searching will not see its potential and powerful use cases.
The difference is this: In Google, most queries end up with a list of links to pages that Google thinks answer the query. In WA, you get the answer. Of course Google has the "calculator" functionality, and that's the directly analogous product to WA. That's a Google killer feature: I query and get an answer directly without clicking around and hopefully, maybe, potentially finding an answer. Whether that's good or bad is a separate subject.
Another more subtle difference: the query is interpreted differently by the search engines. WA's interpreter is much more powerful in deciding how to interpret the query; it also tells you how it interpreted your query. Google's queries are mostly keywords and phrases (and they've noted that the average number of words in queries is increasing), and fundamentally they're still interpreted as keywords as phrases not the meanings behind them.
How queries are written (keywords vs natural language) and how they are interpreted is a big area of innovation in the search industry. I don't think they've finally solved it, but they're certainly trying hard: Hakia, Powerset, True Knowledge, and now Wolfram Alpha.