I've done Italy, Germany, and New England with ABD. My in-laws are Disney vacation club members and taking their family on vacations is their love language. So I have happily participated. They're very nice vacations that come with 2 very personable and knowledgeable tour guides. They do both adult only and family trips, I have only done the family ones, so there have always been kids on mine. I think they keep the groups small enough that you're not traveling with too large of a group which is nice. They do a good job of entertaining the kids while sill keeping them a part of the group. A lot of your experience will depend on the group that you are with, there is a lot of together time on tours, meals, and transportation. If you bond well with the tour group it is a fabulous time, and if you don't - then it can be frustrating. You don't have to worry about any of the trip logistics, and you don't have to plan anything, which is awesome. But could you make a very similar trip happen on your own for a significantly lower price, absolutely.
Haven’t done any ABD, mainly because I don’t see the value. We just returned from a 2.5 week trip to Peru. We booked through a luxury travel company, Kuoda, and I’d highly recommend them! Our 18 nights, all private, guided tour cost us less than one week with ABD, and included a lot more. Highly highly recommend price comparing with Kuoda!