Nevermind I saw the trailer before the Avengers film and have to say I'm glad its only 90 minutes, it looks awful to me, hopefully wrong on that one
Studios tend to care about script page count from a pure business perspective, and a number higher than 108 is usually scary to them. This is before any of them even read the damn thing, if the first draft of the movie they hold in their hands is already over two hours, they are already cautious.
(just for reference, 1 page = 1 minute)
The shorter running time could just be a sign that this production was green lights most of the way, how it all will turn out we will have to see.