Hm, I think the best thing I've learned from books is to be thoughtful about things. And of course, English is very good to learn from them too, whether or not it is ones first language.
And for those who read a wide range of genres - They probably get a lot of general knowledge from that.
As said there I get a whole lot of general knowlage from books (we are just talking about fiction here, right?) and lots of words 'n wisdom. Besides it means I don't spend half as much time on the computer which can only be a good thing
Trouble is a whole lot of words I learn in books I find incredibly hard to fit into a normal conversation, for instance where are you going to fit 'a verbal monolith of ambivlence' into one? I tried using a whole lot of the vocab I learned for a while but I usually just got a 'what?', 'Urrrrrm........', 'Huh?' 'You were saying?' or just got looked at as if I was mad