I am almost positive others have mentioned this @Mark Barnes (Logos) , but my biggest disappointment with Smart Books search is the choices it makes in the top books returned in searches. So many times, the books it chooses couldn't be further from even my top half of resources! It seems to choose from (imho) obscure denominations and authors - none of my more notable resources are used. Of course, it comes nowhere close to looking at my priority list - and often I am asking questions that should have answers in commentaries, not that it's the only solution.
I am not against seeing obscure resources show up, if the question is truly an obscure one that many books will not be helpful in response.
It would be great if more could be done to make Smart Search better at knowing our preferences in resources, to at least start there. Can it learn how to peruse our priority list first, or ratings (we could then "train" it on our own if we don't like the choices), or some other clever way to train it?