Cleaning the oven

Anybody ever used the self-cleaning feature on your oven before? Yesterday was my first time. I had some overspill on a pot roast I made and frankly was being a bit lazy on the clean up. So initiated the self-cleaning and soon it smelled pretty bad (burning) in the kitchen. The fire alarm went off, two puffs of smoke came out of the oven, and I had to open the back door it was so smokey/stinky. Yikes! We wondered whether to shut it off or let it run its course. Needless to say, we stayed home for the four hour self cleaning cycle. Once the cycle was complete I still needed to go in and wipe it down (which is what I was trying to avoid in the first place!) And now my oven is clean :-)