I had a maybe-overambitious second brew that was an oatmeal, coffee, chocolate, bourbon stout. Added 2 kinds of chocolate to the boil, 2 oz of sumatran coffee at 15 min, then cracked 2 oz of Kona coffe and soaked that in bourbon during the primary. After 10 days of primary, racked the beer onto the 2 oz of cracked bourbon coffee and let secondary for FOUR WEEKS. When I bottled, the bitter coffe smell was overpowering and I didn't even want to taste it.
Drank a 22 oz bottle after 3 weeks in bottle: pretty strong coffee taste (and I drink my coffee black) and overpoweing coffee after-taste. Couldn't notice much maltiness or chocolate. Now they've been bottled for 5 weeks and the coffee has mellowed and gave way to a more choclate taste. It's truly a testament to aging some of your brews.
If I had to do it over again, I would add coffee only at flame out, as the oils destroy the head on the beer after a few minutes. Also, I'd only let it sit on the cracked coffee beans for 2 weeks max.