The entire graphics engine has been given a subtle but very noticeable upgrade. Contrast is higher, textures are more detailed, lighting is more dramatic and dynamic. The rubble on the Moon is much more visually defined than before, darker rocks really pop in comparison to pale moon dust on the surface. Venus seems more colorful and the lighting there is superb. Mars didn't seem too different, but it's very monochromatic so maybe hard to notice. Earth similar. Vex teleport clouds seem larger and blacker, obscuring more. Some gun and inventory sound effects have changed (largely for the better). Many inventory items got new thumbnail images, and some actually got appearance changes too (Achylophage Symbiote f.e.). Also it seemed that havestables might have been spawning more... could be my imagination. But I swear Venus had Spirit Blooms freaking EVERYWHERE. I didn't have to look for them, they were all over the place.