I have had two in the past 4 years. The pain when it passed wasn't too bad, but the pain of it sitting in my kidney, or wherever it lives was unbearable. I thought I was going to pass out from the pain.
The last time, I was at home, everything was fine one minute, then within the span of 5 minutes my lower right back was on fire, I was sweating, could barely stand up, started throwing up, and went to the emergency room. They stuck an IV in me, and I was pain free...
The first time it happened I was in a hotel in Washington DC, that sucked because I had nowehre to go and had to just bite the bullet and deal with the pain.
But actually passing it was nothing compared to that pain.