Advantages:
Sulphur deposits - medicinal
Fertile soil - grow food very efficiently ( the reason most people return to volcanic regions after an eruption)
Inexhaustible thermal energy which can be converted to electrical power, so living costs could be quite low.
Tourism related activities. Many people want to see a volcano and the spectacular scenery which tends to go along with them.
Mineral deposits which may be separated and marketed.
Disadvantages:
Sulphur Dioxide gas
Sulphur Trioxide gas
Hydrogen Sulphide
Hydrogen Chloride
These all lead to toxic rain which can kill people and animals and destroy or retard the growth of crops.
Eruption
Volcanic ash
Earthquakes
Landslides
Can't think of anything else at the moment.