Many transitive verbs in Portuguese may have their objects omitted. Either the context will tell what the object is, or there will be no object at all.
Like in "vou comer", you don't need an object, you will just eat, doesn't matter what.
"vou beber", usually means you're gonna get drunk.
"quero (after someone asking if you want something)". The implied object is the one from the question.
This question case is very common. One asks something, and the answer comes without any object.
"Você fez comida?" - "Fiz"
"Você acha que as crianças vão gostar do filme?" - "Elas vão adorar". (do you think the children will like the movie? - They will love it)
I think there must be a difference between "Eles vao adorar" and "Eles vao adorar (lo/la/ele/ela/eso". If you want to use "Comer", yes you can translate To Eat, but you never translate it "To Eat It", so why not follow the same principle here? So, They are going to love, or They will love, should be a valid translation.