Hi Jubilee,
Funnily enough I was wondering the same thing as my MIL got some for DD at the week end. I wouldn't necessarily give them as a drink but mixed with porridge for breakfast for example should be fine.
A word of warning though: Millie was constipated, so I gave her some juice, only twice and in small quantities (1 oz each time) and we had a serious case of diarrhea as a result! It didn't last, but it shows that a tiny amount can really change things!
I now mix fruit puree (which can't be very different from smoothies?) to her cereal to avoid constipation.