This was exactly my experience.

It seemed to take a few months for my body to transition off caffeine. I recommend switching to tea for the first couple of weeks, since that'll at least prevent the terrible headaches.

I definitely feel healthier for quitting the habit, though I still miss "real" coffee sometimes. :(

It was 'just' a solid week of bad sleep, horrendous headaches and night sweats for me when stopping.

Frightening to think of those withdrawl symptoms for such a seemingly innocuous drug.

I once did an experiment and went completely caffeine free.

First three days I was sleepy, then I recovered to exactly the same productivity level.

Then I decided to make me more productive and drunk a 0.25 Adrenaline Rush. My symptoms were nothing less than caffeine overdose.

I wanted to work but was unable to do anything because of total lack of focus. So I wanted to sleep and unable to sleep because fo hyperalertness. Then I wanted to work because I cannot sleep, etc. The cycle lasted for six hours at least and it was very unpleasant. I was even unable to read!

Right now I take a long walk after work if I want to be really productive next day.

I'm going the last 5 days w/o coffee and felt no difference at all regarding anxiety, focus, sleep & headaches. I normally drank 3 cups in the morning (200ml each I'd guess) and 3 after lunch.

Caffeine sensitivity is highly variable between individuals. I am both sensitive and a slow metabolizer; if I had 6 cups of coffee in one day my guts would be churning and I would not be able to get anything done.

I second on the "moody". I've never seen it written about, but, even apart from alertness, caffeine makes me extremely emotional. Bouncing happy to sad in ways I otherwise wouldn't. And at high levels, I blaze with inspiration... with ideas that all turn out to be garbage on later review.

Try combining it with L-Theanine supplements.. Completely removes the tension effects for me.