If you just want to improve the vebral and listening, you can watch some TVB drama (The biggest tv channel in HK). Some of my friends learn cantonese from it. Song is like a poem, you won't always use the vocabulary in that. Chinese is difficult because there are so many meaning in one or two words. Sure if you really interested in chinese word, you can learn it from song. Also the pronunciation of some words when we are singing actually has little bit different with speaking.