I have been able to play this game 1 day early because im in Australia so I thought I would tell you how it runs in handheld.

The environments are pretty detailed and character models are clean. sometimes you will see the occasional few tiny jagged edges but overall its crisp. The cutscenes are marvelous and epic.

As for the framerate it is very solid even with multiple allies and enemies on the screen at once. No frame drops occurred for me so this is a good sign that this is well optimised. Transitions and camera movements don't cause it to dip as expected and this is great

This game would probably look even better docked but for now I am sticking to handheld mode.

EDIT: some people mentioned pop-in so this may be a turn off for some people