I have a knee-jerk reaction to sites that reveal things or animate as I scroll down. It was cool the first time or two…years ago. Now it feels gimmicky at best, and more often it obscures the page in a way that makes me feel like I need to scroll the entire page before reading it so there’s no hidden surprises.
Of course this also boils down to intent - is the page an art thing where presentation plays a part in the interaction? Cool. But I was on a product page for a home media server that did this and it was painful - I wanted specs, testimonials, information, and I had to scroll through animations and slide-in text and all kinds of stuff to get a grip on the -product-