I got to play a bit last night. This game doesn't feel at all like the one that shipped. The planets are more cohesive with newer, more interesting formations, the lighting is better (see below), the plants are grouped rather than spattered randomly, animals can appear in HUGE herds and are more varied, bases are insane (see below), freighters are cool and when I bought mine, the entire sky was filled with freighters and other ships—there had to be over 30 flying around, there are new elements, the elements you scan now show their periodic table abbreviation so you know exactly what is nearby, Photo Mode, draw distance is improved, ship-to-ship battles are more epic, mining tools have levels now, I saw an animal mourning the corpse of its friend/mate and more that I'm failing to remember right now.
Here's the freighter I bought and can customize the interior of. Behind this shot was another 20 ships that warped into view.
Here's an example of the extreme lighting. This planet was insanely cool and shifted to more or less red depending on the time. At some points, the plants and landscape were only slightly different shades of red outlines.