'Ohana is my personal favorite meal in all of WDW.
Like any restaurant, it has good days and bad days, but every meal I have ever had there has been phenomenally good, not to mention huge and incredibly filling.
See here for the menu:
http://allearsnet.com/menu/menu_oh.htm
I also love the relaxed, laid-back, quiet atmosphere of 'Ohana. Even when the kids get up to do the hula hoop contest and coconut races, the restaurant doesn't get boisterous, but everybody has a great time.
Service is usually excellent, although I have occasionally had a sub-standard server. Be prepared to have many dishes brought out to you at once when the appetizers and sides come; some folks think this means that they are being pressured to eat fast and get out, but it's really just that they bring you a bunch of different dishes at once so that you have a choice.
'Ohana is family-style, meaning that it is all-you-can-eat, but they bring it to you. Your food comes out in large serving dishes and you put it on your plate yourself, except for the meats from the grill, which the waitstaff brings to you on huge metal skewers and puts directly on your plate. Tell them which meat you like best and they tend to bring you huge amounts of that meat without even asking.
If you are not a huge eater, let the server know in advance so he won't bring too much at one time. Some folks feel that this is wasteful or feel uncomfortably pressured to eat more and more, but the servers really just want to make sure everybody has enough of everything.
And as tempting as it might be to gorge yourself on the fantastic food, be sure to save some room for the desert, which is the very best sweet treat anywhere in WDW - bread pudding and vanilla ice cream with an unbelievable Bananas Foster sauce on top. It will BLOW YOUR MIND how good this desert is!
Enjoy, and Aloha!