As far as family-friendly, urban farmstyle markets go, it's one of the nicer ones we've been to. Very well laid out, loads of space, great variety of food and products for sale, a playground for kids (R40 buys them full day access), a beer garden with live music, and just a really chilled vibe (mercifully poseur and hipster-free). The animal farm was, however, really disappointing.
Although Riversands Farm Village seems to be open pretty much every day (Tree Tops Adventures, similar to Acrobranch in Melrose, is on the same property), the market itself only happens on Sundays, from 9am till 4pm. I would suggest you go early and leave before it gets too hot. And take cash, as many of the stalls don't take plastic.