Look, I understand that Venom is a popular Spidey villain, but the world doesn't wake up every morning praying to him, like Venom fanboys do. In the their minds, it's just a movie, GASP! It makes no difference, if the majority (fanboys/casual movie goers alike) are entertained and like what they see, like the previous films...you've got yourself a lot of repeat-viewings.
And what close guarded secret are talking about, people have Venom in the avatars from the leaked trailer/TV spot? They've pretty much seen him already. They've already passed judgement on both Topher Grace and Venom, hell, they've even read the entire script summary. And most people (die-hard Venom fans alike--give or take a few) still can't wait to see the film.