I know from direct experience that too much coffee is seriously harmful. Some good advice in the article, though it's strange that no mention is made of decaffeinated coffee - been on it for years and you get the taste that makes coffee enjoyable (not all of it smells gross, though the cheap stuff does - and Starbucks is junk) without the caffeine hit.

Never drink it after midday, though, and always start the day with water, then breakfast.