Automatic irrigation systems are convenient, especially for those who travel. About the only con one can list for them is that, initially, they cost more than the alternative. But if installed and programmed properly, they can even save you money in the long run and help in water conservation. Dead lawn grass and plants need to be replaced, and that can be expensive.
But the pros of automatic irrigation systems can go beyond that. Watering with a hose or with an oscillator wastes water. Neither method targets plant roots with any significant degree of precision. Automatic irrigation systems can be programmed to discharge more precise amounts of water in a targeted area, which promotes water conservation.