We took our daugher down when she was 9 months old and she liked the backpack. But we couldn't rely on it for the whole day, so we brought a stroller too. That was a pain. For the rest of the trip we only used the stroller. But while we had it the backpack was nice. You didn't have to push your little one in front of you, your hands were free. It does have its advantages. A lot depends on your strength, the weight of your child, and how you are at the parks (meaning if you're in and out of attractions, the stoller will be easier, but if you tend to walk a lot, the backpack might be nice)
Hope that helps.
Either way, have fun!!!