Completely retro-gameplay. On par with AC 3 gameplay. Graphics are phenomenal but gameplay overpowers the graphics satisfaction.
Just to name a few, no actual quest or mission log, no tagging of chests or objectives with the bird/eagle any more. Mobile objective(s) that can be a pain to find. Scanning is limited to slow movement only. Thus far, no ranged weapons outside of throwing knives. Climbing is limited to places with handholds only. Fighting is more complicated due to limited defense abilities.
Definitely retro.