Apparently, it's not just about the game failing to live up to the hype. There are also a lot of things that were promised to be in the game that ended up not being there. This post on Reddit details all of those things:
https://www.reddit.com/r/NoMansSkyTheGam...ront_page/
The list is very long. And to make matters worse, even the video on the Steam page for No Man's Sky shows features that do not exist. It's looking less like the game failed to meet expectations and more like players were being intentionally misled.
Not to mention the whole thing about the creator saying that there would be no paid DLC (only free patches) then a week later announcing upcoming paid DLC.