Green tea is usually vegetal and either sweet or bittersweet. Black tea is usually bold, dark and fruity. White tea is very different from both of these tea types - it has a delicate, fruity taste. Some white teas are very floral, taste smooth and sweet.
Preparing white tea correctly is easier than making green tea well, but slightly harder than steeping a good cup of black tea. To make white tea, use water that is under 190 degrees Fahrenheit and steep for three to five minutes. White tea is fairly flexible on its brewing times (I know some people who steep it for seven minutes!). Its brewing temperature needs to be well below boiling, but it isn't as finicky as green tea, and won't be ruined if the water temperature is a few degrees off.
When you are buying white tea, you may also notice that it tends to be more expensive than many black teas and some green teas. This is because real white tea must be hand harvested from the tiny, young leaves of the tea plant. This process is very time consuming and costly, so white tea is more expensive. (Also, it is rarer, which creates more scarcity and drives up the price.)