There's good news and bad news about this cruciferous vegetable. What are the health benefits of eating cauliflower? That's the bad news... for a plant-based food, it contains relatively low total amounts of antioxidants (however relative to practically any form of meat, it contains a lot).
Now for the good news - cauliflower is healthy for you in a number of other nutritional categories. One cup chopped (about 127 grams) is only 27 calories, making it an ideal ingredient in salads and entrees for those trying to lose weight. There are many creative recipes for using it as a flour substitute in things like pizza crust, which create a low carb and low calorie alternative. That same 1 cup amount also provides you with 320 mg of potassium (9% of your daily value), a little vitamin B-6 (10%), and a lot of vitamin C (85%). Though keep in mind that vitamin C is easily destroyed by the heat of cooking and that amount is based off of raw cauliflower.
The last piece of good news is that cooked cauliflower is good for you, almost just as much as the raw form. With many fruits and vegetables, the antioxidants experience degradation from the process of cooking. With cauliflower this does occur, but the cooked version still has a comparable ORAC value.
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010