You can walk up Mt. Aperture in jogging shoes, but you need to clear the moat of change that surrounds it. Put more directly, the learning curve is gentle, but it is not attached to anything anyone is used to. The paradigm for a loss-less workflow is nothing like the paradigm for file management and manipulation that we now use without thought.
I have written a concise guide for those getting started with Aperture. The program confused the hell out of me, so I thought it worthwhile to build a small bridge for those trying to make the same leap. It is now a User Tip on
Apple's Aperture forum.