I am in the no juice camp. Esp b/c DS has some serious dental issues we're dealing with (not due to juice, but can be made worse by too much sugar).
However, he does get juice on occasion. First, he eats a very healthy, complete diet otherwise. I don't feel like 50 cal worth of watered down apple juice is going to undermine that. And second, he's like me and when he has low blood sugar (sometimes first thing in the morning, or after he's been playing vigorously outside in the heat), he becomes Mr. Meltdown. One juice box later, and he is back to normal. But juice is not a daily occurrence, and we purposely keep juice in our spare fridge in the basement so that it's a big PITA to go and get it. And finally, if it's been a couple of days since he's pooped, a little apple juice, and he is good to go, as it were.
FWIW, DS didn't have any juice until he was about 18 mos old.
mommy to DS who is 9
DD who is 6
and my girl in heaven