From what they have demoed, they have not proven that anything actually is being generated. My best guess is that they randomly vary colors and textures (and generate the atmospheres, as they say), and randomly place models about the planet, which is a far cry from actually generating all of the models and animation for everything. A lot of it just looks modeled by an artist (and they do have an artist on their team). Anyhow, I don't think this will necessarily detract from the game, just a nitpick on choice of words...
An additional concern is how quickly this game came out of nowhere (I think?). The Inovae (formerly Infinity) engine took many years to develop - it was one of the first of its sort to allow seamless planet to space transitions with tons of terrain detail. If you look in close detail at the differences between the two, you can tell that No Man's sky does not have a very good sense of scale when flying into a planet (unless the planet were incredibly tiny). Also, note the angle of the fly-in is straight on; its much harder to prevent detail popping when flying in tangentially to the planet and I wonder if they have yet addressed this. Again, just another nitpick. :)
No Man's Sky (2:00 in for the planet fly in): http://www.youtube.com/watch?v=nLtmEjqzg7M
Inovae/Infinity: http://www.inovaestudios.com and http://www.youtube.com/watch?v=a6a69dMLb_k