After watching the First Looks, the best thing I can say about No Man's Sky is that it does not warrant a preorder, and that I need to see something more in order to buy it. My more realistic evaluation of the game is that it is turning out exactly like I feared. The game has a lot of things to do, but none of them look particularly fun.
1. Watching the game is not the same as playing the game. Watching somebody walk around on a planet and shoot at minerals is boring. But walking around shooting at minerals yourself, knowing exactly what piece of kit your saving for, and how that piece of kit will let you take on that bounty mission, or fly to the next system, or learn more about an alien race etc -
is fun.
In your head you're having your own adventure while you play. You won't get that from videos.
2. The game is incredibly huge. I'm not talking about the procedural stuff. It has thousands of pages of story/lore which is surprisingly well written, choose-your-own-adventure quest paths, an actual backstory path which seems to progress with you, some mini-games and extra side activities to discover.
Watching a stream for half an hour might show you 15% of the game's content, or it might show you 0.01% of the game's content.
You can't judge from videos or streams. Play it yourself.
One thing that I hadn't realized, but in hindsight should have, is that once you figure out the randomization techniques used in the game, they will cease being able to give you the illusion that you are exploring an expansive galaxy. At that point it won't matter how many planets there are because when you see a new one it will just remind you of different combinations of things you have already seen. For a game whose main hook is exploration, this is a fatal flaw.
It's an incredibly complex system. There seems to be a 'median' sort of planet and animal generated - you'll come across similar things quite often - but then out of nowhere you'll encounter a totally fucked up place or a type of animal you've never seen before.
This keeps happening to me. I'm 15 hours in and I'll visit four planets seeing similar sorts of stuff - and the BAM I encounter something I never expected that is almost scary. The exploration is rewarded tenfold because of moments like this and they make up for planets upon planets of similar stuff.
It's a big universe with an incredibly complex procedural engine behind it.