It's a pretty short game all-in-all. Took me about 9-10 hours to be done with it completely on normal. I found the narrative to be the weakest part of the game, something we've become accustomed to when it comes to Sucker Punch. Lots of underdeveloped characters and a very ordinary plot.
The game makes up for those shortcomings through the game play. Everything is so well implemented. So fluid, so smooth. The kind of powers the MC has control over, you'd expect to hit some sort of technical snag along the way but I've yet to face anything of the sort.
Second Son is a visually resplendent, technically sound game that might be a bit lacking in the content department but it's definitely a big step up from the resounding disappointment that was Killzone shadowfall.
As per the OP, out of respect for the meta, my prediction for the metascore would be in the 80-85 region. It might even dip below the 80 mark. Although it's a technical marvel, I fear the weak narrative and sparsity of in-game activities might not put it in such a favorable light in the eyes of reviewers.