It has certainly changed our experience, and while we thought we might regret it, instead we've added on twice. We were almost perfect
DVC candidates in some ways; we were going to WDW approximately every 9 months, we always stayed club level in deluxes, and we usually got 2 rooms or a large suite. We were worried we would miss concierge amenities, the included alcohol and snacks, and daily mousekeeping.
What we're found is that we set up our own "club level" lounge in our kitchen. We have snacks for the kids, alcohol for us, and food for easy breakfasts, and it is better and cheaper than we used to get in the lounges. It's also less crowded and has a better view.
I really prefer to book my own meals and activities in advance, so I don't mind not having a concierge at hand. We don't miss the mousekeeping at all, and have gotten to where we prefer not being interrupted.
We love having the extra space at a really good price. It's definitely saving us money. We may go a little more often, but not much more than we'd go, anyway. We find having the kitchen, the washer dryer, and the extra space adds to our vacations. We try to always get great views, and what could be more magical than sipping your coffee on your balcony while you watch zebras chase each other and giraffes eat their breakfasts, or relaxing at night watching the fireworks on your own balcony.
Staying in a particular resort before you buy is generally a very good idea. Even if you're pretty sure you know you want DVC, you may be surprised by which resorts you fall in love with.