We went there last year on one of our "No Park" days during our last one week WDW trip.
It is free. You can walk through the horse stables, pet various sheep, goats etc. and there were even chickens and peacocks roaming around. There is also a pure white peacock.
There was also a man there that helped you get your child situated on a pony and then walk your child and the pony around a small paddock. I believe the pony ride was free or something very minimal but I am not 100% sure because my daughter was too little at the time.
Sometimes the blacksmith shop is open and you can watch the man, who shoes all the MK draft horses, work.
Well worth a "Quiet" day!
We are going again this upcoming trip, right before the Hoop Dee Doo.