Firstly almost nothing changed since the 2015 trailer, just the UI is now way more optimized which pretty much proves that CC2 leaving didn't seriously impact the contents of the game.
There's now a shortcut menu exactly like Kingdom Hearts that let's you assign special abilities (such as limits), items and likely magic as well to the 4 face buttons. What's interesting here is we can see Tifa and Barret are displayed on this menu too; assigned to L2 and R2 respectively.
Cloud appears to block a big attack from a mech enemy, yet there doesn't seem to be any indication as to how they're doing that. If square and triangle are regular attacks and circle is the menu, that only leaves X as another dedicated block button. This would mean there is no jump button in the game, which isn't the end of the world, but it'd be strange in an action rpg.
We see some ledge hanging as well, briefly. Whether this is a scripted event like the ones in XV or its more organic like KH3 is yet to be seen.
One major concern was the complete lack of hitstun from regular attacks (which you can observe when Cloud performs a full combo on a small enemy in the footage and they don't flinch or react at all to his attacks). This is an issue in an action oriented game as your attacks won't have any weight and it'll feel like you're swinging a small stick rather than a giant metal Greatsword the size of a small human.
It also seems that the Materia command was completely removed from the UI but you can still see material skills like braver in the shortcut menu along with healing items etc, plus you can also see the materia are now visible on the buster sword, i mean the actual materia spheres are installed on it and are visible which i think is cool as hell .
All in all the game looks very similar to PSX 2015 but vastly improved, very promising trailer.