There's a time and a place for full auto. Here's how I normally find myself using it...
Down the battle-cruiser for a few jars with mates. Start on manual mode. All is fantastic. I'm controlling the DoF and motion blur in my photographs. Fantastic results; sharp, contrasty, colourful. Composition and technique are spot on (for me, anyhoo). You could show these pictures to your folks and they'd be impressed, thinking you're a model citizen. Even the local paper would snap them up to show that not all mid-to-late-twenty-year-olds aren't binge drinking trouble makers.
After a few pints of ale, I can no longer be bothered with manual metering and faffing about with shutter speed so I find myself slipping into aperture priority. Still getting some great shots, just not as finely tuned as before drinking started. The flashgun is out for a bit of fill here and there, bouncing it from whatever I can to get some nice diffuse light. These will be great for mounting on bedroom walls, posting to Facebook, or showing to siblings with a good story about the night.
Now some idiot goes and buys a rack of shots. Fantastic idea. We're all knocking them back and the light is getting lower all the time, if there's any natural light left. f/whatnow?! Jeez this gear is getting heavy. Screw this... flashgun back in the bag, full auto, on-camera flash pops up and I'm snapping away like a tourist in the West End. The photographs are becoming obscene. "Dude! That photo's hilarious! Quick... get one of that girl's boobs!".
Now I'm absolutely trollied and the camera goes in the bag before I drop it, spill booze all over it, or start taking unacceptably inappropriate photos. Wake up the next day, feel the massive hangover and see camera in auto mode. Shudder. Download photos and spend the rest of the day giggling, cringing, deleting...
All in all... full auto, at least for me, is for when I'm completely wasted and can't be bothered with anything resembling good photographic technique.
George.