To me German does sound slightly angry, but also rather technical and precise, if you where giving directions or explaining how a car engine works German would be suitable. It's defiantly a mans language.
Japanese sounds very jittery and bouncy, as well as loud, it's words seem like quite a mouthful. Japanese, like German, also sounds a bit angry.
Chinese sounds even more jittery and bouncy and even more of a mouthtful than Japanese is, to the point that you carn't really take it seriously and it loses the anger which Japanese has.
French sounds rather wet and slushy.. can't really elaborate. Spanish sounds more vibrant and is a bit of a mouthful, it sounds like a rather passionate language.
Russian sort of sound's angry, but it't too fluid to be truly angry, Russian is the sort of language which rolls off the tongue and everything seems to rhyme, it's a liquid language, like their vokda.
That's all the languages i've heard enough off to provide a suitable commentary.
Btw, it's just occurred to me why English speakers see German as an angry language. For most people, when they hear German, it is whilst playing a video game or watching a movie and the Nazi's are yelling something along the lines off hande hoche!!or Halt! Englander! or schissen der Amerikana!