I love coffee. I drink about 1.5L to 2L of it a day. My espresso machine gets quite a workout every day.
I recently, however, switched to decaf. It was a terrible couple months during the transition (half-caf then to decaf) that I had constant headaches, couldn't sleep right and my hands trembled. I switched because I was having significant issues with my hands shaking and getting headaches on the weekend when I didn't have an adequate caffeine intake early enough in the day (since I'd be out of my work-day regimen). I now have a terrible reaction to caffeinated coffee and cola - though tea leaves me largely unaffected.
I don't regret switching to decaf but I am always disappointed by the much greater selection of coffees available with caffeine vs. decaf.
I can, now, wake up on a Saturday morning with a glass of orange juice or water with breakfast with no ill effects of skipping a coffee.