Hmm. It's a lovely idea but I find the results uninspiring. (Which isn't surprising; it's a very difficult problem. But I was hoping to be amazed.) Here are the examples I tried (all of them, no cherrypicking):

daughter + male - female -> { The Eldest (book), Songwriter, Granddaughter }

(Hopeless; should have had "son" in there)

pc - microsoft + apple -> { Olynssis The Silver Color (Japanese book), Burger Time (arcade game), Phantasy Star (series of games) }

(Hopeless; should have had "Mac" in there)

violin - string + woodwind -> { clarinet, oboe, flute }

(OK)

mccartney - beatles + stones -> { Rolling Stone (magazine), carvedilol (pharmaceutical), stone (geological term) }

(Poor; should have had Jagger or Richards or something of the kind in the top few results)

sofa - large + small -> { relaxing, asleep, cupboard }

(Poor; I'd have hoped for "armchair" or something of the kind)