I used the old formula for my first two babies and loved it. I was really sad when they went off the market when my third child was a newborn and I hoarded every bottle I could find.
We were part of a sample give-away when they came back with the new formula. My baby was about 9 months then and in need fo teething help! My baby is now 2.5 and has used Hyland's through getting all of his baby teeth, and my older children use them when they have molar pains or growing pains after losing a baby tooth.
We have found that Hyland's works consistently and quickly for all the above situations. It's pretty much all I've needed to use for easing the pain of teething for my children. I recommend it very highly.