That airbags save lives is well documented, but keep in mind that you have the air-bag system serviced by properly trained professionals after it has deployed.
An air bag is designed for ONE USE and cannot be "repacked" after it has deployed (ditto with motorcycle and bicycle crash helmets). In fact, the air bag and many of the system's parts are not "repairable" and must be replaced. The parts are designed for each specific vehicle. For the system to function correctly if the vehicle is involved in another collision, the proper parts must be purchased and installed by a qualified technician. Your life (or the lives of your passengers) depends on it, whenever you have your next accident.
If you are buying a used vehicle that has an airbag, ask if it has ever been deployed and, if so, where the system was replaced. The airbag should be inspected as part of a mechanic's inspection prior to buying any used vehicle.