With Nikon's flash metering, you can point and shoot and get consistent exposures. With Canon's ETTL, to get consistent exposures, esp with the D30, you have to get into the habit of preflashing at your subjects, as the flash metering is weighted towards the active focusing point(s).
What this means is if u focus on the subject and recompose, the active focusing point will fall on the background, and the flash system will meter for the background. (overexposure most of the time.)
the solution for that is to use auto focusing points, move the focus point over the subject, or preflash at the subject and recompose.