Narcoosee's is a signature restaurant, so it is a bit more upscale than some other WDW restaurants. Children are welcome there, and there is a kids' menu, but meals do take a long time, and there's not anything going on to entertain the kids. If they can sit quietly for a couple of hours, it'll be fine.
There's a small deck area just outside the restaurant, so if the kids get restless, one parent could always take them outside for a walk.