Be lucky that German still has enough vowels between consonants (maybe except "psst", an echoism like "shush"). Some words in Polish or
Czech have none at all.
BTW, German does not always sound as brutal as in songs by Rammstein (part of the genre "Neue Deutsche Härte" ~ "New German Hardness", a play with "New Wave" based on "Neue Deutsche Welle", you might remember Nena's 99 Red Balloons, maybe). Fans of Heavy Metal are surprised that the oh-so-german-hard-looking Umlauts in band names (Heavy Metal Umlaut) like "Motley Crüe" or "Mötörhead" in fact change the pronounciation to a soft, cute sound instead, not at all "metal".
"ä" (oe) sounds similar to the "a" in "bad", "sad" in American English or short in "match"; the "a" instead is usually spoken like in "car" or "but"
"ö" (oe) sounds similar to the "u" in "burn", "turn" or short like in "curry"; "o" is pretty the same as in english ("more", "pot")
"ü" (ue) is a bit harder to compare, maybe like the first "y" in "mystery" with

pursed lips; I don't remember any sample of a long spoken similar sound in english

"ß" (sz) is a rather sharp "s" with some pressure (in the reformed German ortography, "ß" is now only used after long vowels, but "ss" instead after short ones), while "s" in German may be preferred as humming like the english "z" sometimes (depending on the position), and the german "z" instead sounds like "ts" (and with a little more pressure in "tz" like in "Ritz").