Has to be plain English for me and don't go round the houses, get to the point - just finished a book in triple quick time 'cos he used twenty words when ten would have been enough - so I sure did scroll through them pages
I am not intimidated by words and even when I come across one that I haven't encountered before, I can usually figure out its meaning by the context. But I won't bother with it if it's not otherwise interesting. Authors who use complex words, when simple ones would do, are rarely compelling.
I enjoy the challenge of figuring words out by context also, but like others, I don't enjoy books that are poorly written or written by someone aiming to show his/her intelligence. My idea of an intelligent author is one who is plain spoken and writes for his/her audience. I have a sufficient vocabulary for most books I choose, and it's rare that I come across one with more than one or at most two words I don't already know. I have read enough textbooks in my life, and now prefer easy, interesting reads.