My fiance and I just completed this Saturday! We weren't really looking forward to it (him especially), because giving up nine hours on a Saturday (even though obviously it's for a good cause) is not that appealing, especially when it's snowing out. But we planned a fancy dinner for afterwards to give us something to look forward to, and headed out in the snow.
But it wasn't that bad! I actually really enjoyed it, and the nine hours flew by. The leader couples were all really interesting, and had really valuable things to say about fighting fair and being patient (these were the ones that stuck out to me). I wished there had been more specific information about NFP and about financial advice, but I know they can only do so much in one day. Also, one couple at our table (which had one leader couple and three engaged couples total) was really apathetic, which made it uncomfortable for the rest of us to really open up and get into it during our small group discussions. They also fought the entire time during our short breaks...
So I guess my message is don't dread Pre-Cana, you might actually end up liking it!