I just tried giving the book to Gale, he starts reading it but never acquires any skill. The book also never leaves my inventory, even though I'm pretty sure it should (if you give it to Astarion he won't let you take it away from his inventory - it would be nice if Shadowheart could do the same with her stuff bth).
I also tried offering it to him as a snack and even then the book does not disappear from my inventory, so it's basically a free food dispenser for hungry mages.