I think there are a lot of variables and it depends on the person.
For example, some studies have shown that a bit of caffeine before a workout can actually boost productivity and energy while exercising. It can also boost calorie burn (slightly - it's not a magic bullet).
Also a cup of coffee or tea each day has been shown to be beneficial to heart health, especially in women.
On the other hand, too much caffeine can have a diuretic effect, which can be counter productive if you're trying to make sure you're drinking enough water.
And some people are sensitive to caffeine and it can make them edgy, stressed, and even mess with their sleep patterns.
I think it's something that everyone has to figure out for themselves, ultimately. I personally drink about the equivalent of 2 cups of black coffee in the mornings (1 large DD coffee). Then I don't drink coffee the rest of the day. Maybe 3x a week I have a Diet Coke in the afternoon - usually when I'm craving the fizz and flavor of a soft drink. But I never drink Coke or coffee after that because I know it will make it hard for me to get to sleep at night. If I do go out to dinner and have coffee after, I make it decaf.