I had experience with this on the Pride back in October after the restart. I was not impressed. I'm celiac and cannot have gluten. I have cruised numerous times on Carnival and pretty much know what I can have and what they can make gluten free (french toast for brunch, pasta for dinner, for example, can be made gluten free). When trying to order my meals at dinner for the next day, things that are gluten free were not showing up. I wanted Indian veg one night which didn't show up. My waiter refused to place the order for me because it didn't show up as gluten free in the program. French toast didn't show up - "you can only have the parfait." One night for dinner, it only showed a salad...
I made sure to give feedback about it after my cruise but was delighted that the Legend didn't seem to use the system when I sailed in February. Not looking forward to it going fleetwide, unless they've made significant improvements.