We ate dinner at 'Ohana's last October, and it was delicious! My 4-year-old ate a little of the turkey, but we asked for a hot dog and fries, and she enjoyed that a lot more. At first, she was too shy to do the coconut races and hoola hoop contest, but when they did it the second time, she finally participated and enjoyed it.
Try to schedule your dinner for about 1 and 1/2 hours before MK fireworks, because you can see them from 'Ohana's if you're anywhere near a window (and the music is piped into the restaurant). If you're nowhere near a window, and you're through with dinner, you can just go down to the Poly beach to see them. Enjoy!