I am German and we didn't get all Siri features before iOS 6 (wolfram Alpha is still missing). But I tried it more in the last days and am really impressed! Even when I thought "oh, I mumbled the word, Siri won't get it" it was correctly recognized. I most use it as text to speech for SMS. And checking Fußball Bundesliga works good. (But only first league, no info available for second league.)
Since iOS 6 (or at east I never noticed before?) there is also an info button on the Siri screen which shows example querys/commands. This hels a lot!
I'm from germany too - I mentioned this before, but did you notice that you can't speak to Siri in english at all when its set to german? This is problematic when telling Siri to play music by any artist whose name, band or album is pronounced in english - a native german name would work though.
This, I guess, would apply to every non-english country and seems like a quite an oversight rendering music controls via Siri useless. Since english words and expressions became natural parts of every language, and are also pretty common in artist, movies, brands, places, etc, Siri should always check back with its english dictionary regardless of language settings.
Since iOS 6 (or at east I never noticed before?) there is also an info button on the Siri screen which shows example querys/commands. This hels a lot!