Not much really, since the trailers had already spoiled that pretty thoroughly for me
edit: and as for them not being all clones anymore, from what I remember of that discussion around the time the movie came out (which I suppose isn't spoilery anymore, as Keybounce saw him without the helmet), wasn't that fact established by the OT itself? Because there's something in A New Hope (which I don't recall from the movie, just from the discussion) about how Luke was thinking about becoming a Stormtrooper before Ben showed up and all? So, by that point in the timeline, at least a significant portion of the Stormtroopers, perhaps all of them, are conscripts rather than clones.