'Ohana is fun for the kids with the activities and singing, it's loud and the kids can get up a participate in the sing-a-longs and coconut races. The food is terrific and the kids can order from a kids' menu and/or eat the served food. It's a nice sit down, all you care to eat meal. I love the food at 'Ohana and couldn't go to WDW without going there. The grilled meats are fabulous, the dumplings are crispy and tasty, the salad has a dressing that I wish was bottled and the bread pudding is fantastic.
We have also enjoyed Boma with our kids. I have one adventurous eater who loved it and a not so adventurous eater who also loved it. There are plenty of kid friendly choices plus salad bar, fruit and lots and lots of desserts. Atmosphere wise, not as interesting for kids as 'Ohana, since there's no entertainment, it's just an eating experience. In my opinion, it's not too spicy or too different in any way, my DD11 was willing to try everything.
We've done both meals with extended family--Ohana is especially nice for larger groups since it is a sit down, served meal. At Boma, we were a little cramped and, eventhough the restaurant is open, it's sometimes hard to find your way back to the right table. We also felt a little abandoned on the service side at Boma. Both are in great locations, Boma was a wonderful excuse to hang out at AKL. We enjoyed drinks before dinner at the lounge that overlooks Boma and I was surprised by how uncrowded Boma was during a peak week (school break).
I'd also mention that both dinners are so different that it's no problem to do them both on the same trip. 'Ohana breakfast is also a lot of fun, so if you want to break it up but still visit 'Ohana, I'd recommend dining with Lilo and Stitch, too!