I started out with a DSD program myself. Watched a video and filled out paperwork at the shop along with a wetsuit rental the day before, then met the instructor at a community pool the next day. Got a brief overview of equipment and did a few comfort skills - which we did so well the instructor had us try no mask breathing (face down, standing up). Then some fin pivots, shallow swimming, misc other skills and a slow move to the deep end, where we were pretty much turned loose to play around. The other woman who was in the DSD with me was having trouble bouncing through the water column, but he figured I was comfortable enough to go off and have fun. On the debrief we were told many of the skills we did weren't normally part of the session, but were a "see how you do" thing - and told that many open water divers exit the class with less comfort/control than we had shown.
From my green-as-grass instructor perspective, I think it was an utter lack of control - but at the time, I think it's part of what made me go on to the full OW cert. Not only did I feel confident, but I had a blast. When I went to OW - it a cakewalk, so much that I was actually told to stop doing skills ahead of time (like a perfect hover on CW2). I can't say I wouldn't have gotten into scuba diving had it not been for a DSD, but with the opportunities that followed I doubt I'd be nearly as hardcore about it as I have been.