We bought Freestyle cups at the beginning of August and as we bought 4 of them they were $9.99 + tax each (over 3 they were this price) and then it doesn't matter how many you have the next day they all cost $5.99 + tax for the days use.
We found that as we were there when it was supper hot, we got more than our money's worth out of them on both days we were there. If I was going at another time of the year when it wasn't super hot then I might have gone with the regular refillable cup.
There were plenty of Freestyle machines and the lines at them were not too bad. I would say that at certain times of the day the machines would be run out of ice or the added flavours but this only happened a couple of times and when we were at IOA until the very, very end of the day they had a Freestyle machine up and working so we could get a drink as we walked out whereas all the other vendors were closed and gone for the day.
The Freestyle options of drink were great with lemonades, PowerAde, flavoured waters as well as the usual Coke, Diet coke etc. gave us all a multitude of selections with the benefit of not always having to have fizzy drinks.