Here are some of the health benefits of coffee (sources available through wikipedia). As you can see, it has been VERY well studied and it is very good for you:
Studies suggest coffee consumption reduces the risk of Alzheimer’s disease, dementia, Parkinson’s disease, heart disease, diabetes mellitus type 2, non-alcoholic fatty liver disease, cirrhosis, gout and cancer of liver, skin, prostate, bowel, brain, gullet, colon, endometrium, breast, mouth and throat.
The fact that decaffeinated coffee also exhibits preventative effects against diseases such as prostate cancer and type 2 diabetes suggests that coffee’s health benefits are not solely a product of its caffeine content.
Specifically, the antidiabetic effect of caffeine has been attributed to caffeic acid and chlorogenic acid.
The presence of antioxidants in coffee have been shown to prevent free radicals from causing cell damage, which could lead to cancer. Antioxidant levels vary depending on how the beans are roasted as well as for how long. Evidence suggests that roasted coffee has a stronger antioxidant effect than green coffee.
Coffee is no longer thought to be a risk factor for coronary heart disease. A 2012 meta-analysis concluded that people who drank moderate amounts of coffee had a lower rate of heart failure, with the biggest effect found for those who drank more than four cups a day.  Moreover, habitual coffee consumption is associated with improved vascular function. In a ten year study among 50,739 US women (mean age, 63 years) free of depressive symptoms at baseline (in 1996), coffee consumption was negatively correlated with risk of developing clinical depression.
A review published in 2004 indicated a negative correlation between suicide rates and coffee consumption. It was suggested that the action of caffeine in blocking the inhibitory effects of adenosine on dopamine nerves in the brain reduced feelings of depression.
Coffee consumption is also associated with improved endothelial function.
Coffee extracts have been shown to inhibit 11β-Hydroxysteroid dehydrogenase type 1, an enzyme which converts cortisone to cortisol and is a current pharmaceutical target for the treatment of diabetes type 2 and metabolic syndrome.