As I say in my earlier comment above, my estimation of this score has gone up from my initial reaction to it but I think it cannot be denied that Williams has done this style of kiddie flick scoring many times before. Parts of this score sound stylistically if not in melodic content very much like Home Alone, Hook or Harry Potter. I guess it is his "children's" voice with which he addresses movies involving children and child-like situations.
I am certainly not saying that there are no singular ideas in the BFG as e.g. the prominent woodwind writing for the dreams and catching dreams is very effective and new and lovely. There are several little melodies that I find absolutely endearing, like the leaping waltzing travelling theme, the forlorn piano melody denoting loneliness on the The Witching Hour and There Was a Boy tracks, Sophie's theme and the BFG's own gentle tune or the whimsical Dream Jars and Dream Country with those prominent flute parts. Williams has always been a master at conjuring the storybook ending feeling of "and they lived happily ever after" and the Finale is another great example of that.
Also this score is the woodwind antidote to all the modern film scoring which seems to shun the entire woodwind family at times. The flute writing is definitely a highlight.