I recently bought a viola myself. It is indeed exceptionally suited to playing airs. A violin player should get good sound out it almost immediately. The big snag is learning to read music in the alto clef. Not rocket science, but surprisingly awkward to adjust to. It is a pity the viola has not been treated as a transposing instrument, like many wind instruments which greatly facilitates switching between them. If you want to hear viola in use as folk instrument, then Sean Keane, of the Chieftains, uses it on some tracks of his solo albums.