Adelaide is a good place to live but not to visit. The population is small, the city is accessible, the roads are simple, and prices are reasonable. All of that makes for good everyday living but, apart from the occasional event, it is very quiet here, which works for me but it's a factor for some.
The climate should be what you are looking for. It does get hot but the regularity to which it gets very hot is overplayed. The more relevant point is that it never becomes very cold. Adelaide is not a place to find snow, a cold day here only gets as low as around 7 degrees C.
