We don't feel that juice is necessary in our child's diet. Sure, it's considered a fruit serving (to some), but considering our son already eats too much fruit in a day, we figure why give him juice that doesn't contain the whole fruit that's meant to be eaten. We believe it's important to eat all parts of the fruit that are able to be eaten.
Another reason we've chosen to delay introducing juice - we listened to the advice of MANY friends of ours. We are told constantly that their kids do not like to drink water and will only drink it if it's flavored. I'm not against flavoring your water with some natural fruit juices, however I'm brought back to my struggles now as an adult and my lack of drinking water as much as I should. I do not like the taste of water...I don't even like the taste of flavored water. I don't want my son to be in the same boat later in life knowing that water is the most important beverage for you and not liking to drink it at all.
My niece, who is a couple months older than my son, stayed with us for a couple months recently. She was not a water drinker at all. In fact, she made awful faces when she realized her cup contained only water and threw her cup on the floor. It took about a week, but with us consistently offering only milk in the mornings with her breakfast and water every other offering, she slowly took to it. In fact, she began gulping it down faster than our son at most meals! One thing we found to work very well with her was to offer her 8 ounces of water in the morning right when she woke up, before breakfast, and guess what? She drank it down so quickly that we hadn't even had breakfast prepared!
We also take the advice of our pediatrician, which I've also heard years ago before ever even considering having children, which is to offer what you prepare (food or drink), if they do not want it, cover the plate (or put cup in refrigerator), and when your child asks for food or drink later, offer what you offered earlier that they did not accept. Our doctor said there will be days you wonder how the child even survived the week because he/she ate so little, but there will be weeks you wonder where he/she put all the food they consumed. We haven't had to implement that rule yet since our son is a pretty good eater/drinker. However, I know we could be dealing with it soon!
So, for now, it's only water, raw cow's milk (or organic if our monthly supply of raw milk runs out) and breast milk. Eventually he'll definitely get some juice occasionally. But it won't be an everyday beverage in our house. I see it as being more of an apple or orange juice on weekends when we have wonderfully big breakfasts!