Wonder what he means by "don't expect mind blowing graphics out of the box"? Does the game start out ugly and gradually gets prettier? lol
No it means the game while is artistically nice looking. It's not going to ever be a technical pretty game along the lines of something like Uncharted 4.
It's because of this game is less demanding on the GPU side of things and is a more CPU heavy sort of game shows promise with the frame rate.
Just because NMS is an "open world" game, people assume it have the same performance as something like The Witcher 3 or Fallout 4.
How the world is generated in No Man's Sky however is not the same (There are no prebaked assets or large texture files requiring load), so in terms of world generation and performance, one should look at other procedurally generated games as a reference point for performance.
Elite Dangerous on XB1 for example has a variable framerate (60FPS in the arena, and 30FPS when in Exploration Mode), Minecraft is also 60FPS on the PS4) as an example.
People might scoff at the Minecraft comparisons, but remember in regards to the world and terrain generation, NMS is doing similar things that Minecraft does, but on a substantially bigger scale.
Sean Murray said each planet is a large voxel cube with a mesh applied that gives it the appearance of a "Sphere"
The world of NMS is being made up of Voxels as opposed to other games which have sizable polygon assets, textures, and shaders applied over top. It's one of those games which the artwork and aesthetic pulls off the look visually and not because of fancy graphics tricks.