[somberi]

I suggest Madurai Mani Iyer's renditions if you are looking for expertly rendered (from a puritan's POV) and hugely entertaining introduction. Two sample songs: www.youtube.com/watch?v=ya5fDVfmx_g and https://www.youtube.com/watch?v=7shwQLX6DTA.

Qawwali is similar to accapella and thrives on a cyclic rendition (similar to nordic "Yoikking"). Thematically, it takes both God and Love as themes and treads softly. Most Carnatic songs are directly about God and builds on the listener's knowledge acquired elsewhere to bring "completion". An example is "Hecharikaga Rara" depends on you knowing the statue of Rama was lost in the River Cauvery and Thiagaraja, the composer finds it and welcomes the deity home)