may be OK for parties, etc but I find these frustrating
it only goes off when light levels are too low to give a shutter speed faster than ~1/60th sec, if flash is up, camera will set shutter speed to 1/80th to minimise motion blur due to ambient light and fire the flash with auto exposure.
if ambient light gives a shutter speed shorter than about 1/80th sec, flash WILL NOT fire and this means you may end up with faces lit by tungsten or flourescent ambient lighting with nasty shadows and perhaps wrong WB which you had not intended ⇒ to force flash to fire, set it to the lightning symbol (ie. Fill-in flash).
it's not available in following exposure modes: M, S, night portrait
in AUTO exposure mode on the dial, it will also automatically popup the flash if you have that functionality enabled in the menu system.