We didn't buy to "save" money - so we don't have regrets. We bought because we realized that while our kids were little, we wanted to take more Disney trips - DVC is an enforced vacation for us - we need to use the points or lose them. Most DVC members don't have regrets.
If you currently travel every year (or every other year), stay in Deluxe hotels, will stay in DVC studios and not change your habits other than booking a DVC resort (or cooking in your room), and don't book last minute trips, DVC probably will save you money over the long haul (I say probably, because if Disney made an offer like the FTP permanent, many people would regret DVC). If you stay in Moderates, the savings is a little harder to justify, but most people believe they come out ahead. The problem in spending more comes when DVC changes your habits - you book a bigger room, you go more often, you stay for longer, you invite friends and pick up their room (few people outside of DVC do that, but nearly all DVC members share), you figure the room is "paid for" so book expensive Cirque tickets you'd never have booked before.
DVC does make these "spend more" habit changes very attractive, but they certainly aren't mandatory. No one is "making" me go to Disney more often, invite my mother in law along, or book a two bedroom.
But if money is tight, I can't recommend DVC. The original contract is not cheap and you will need to commit to paying dues every year. Then again, if money is tight, you probably aren't a yearly Deluxe resort person anyway.