Palladium has been making a come back of late and is in the family of platinum metals. It is considered a good alternative to platinum, a metal that it's very similar to in chemical properties and appearance. It is a lighter metal than platinum -- platinum is almost twice as dense as palladium -- and so palladium is closer to gold in price. When palladium is scratched, the metal becomes furrowed just like platinum, so none of it is lost.
Palladium falls somewhere between white gold and platinum in its ability to retain its shine and the setting of its stones is superior in security to white gold. However, unlike platinum it can sometimes become brittle when worked down. This means its a better choice of metal for designs with less detail, such as wedding bands.
Palladium is naturally hypo-allergenic and because there is minimal mixing of metals to make it strong enough to wear, it has high purity. 18ct white gold rings are made of 75% gold while palladium wedding bands are made of 95% pure palladium.