From the highlight video I just watched, he looks incredibly raw, but Palmeiras fans seem to rate him highly, so we'll see.
It made me laugh seeing the stark contrast in defending styles between he and Khusanov - the latter slides into most challenges and uses his physicality but in the 8 minute video I watched of Reis I didn't see him slide/dive in once.
They seem chalk and cheese and that should (hopefully) result in an ideal partnership in years to come.