it's gonna be a wild spoiler storm... I can never resist them. I was glad I read spoilers for the last 4 movies though, cause they prepared me for the odd things I didn't like.It's getting clear by some comments on twitter and in the media that some people have already seen the first episode. Presumably the review embargo has to be lifted by Wednesday though, because you don't want to have rando Brits who paid admission writing reviews before the professionals.
If I hadn't read that Spock is more emotional and Vulcan is destroyed, and Harrison is Khan, it would've bothered me more. Vague spoilers like impressions or "some known thing will appear, and it's awesome if you liked that old episode..." can be quite interesting as long as they don't reveal every detail.