There are many games that have come and gone that have filled the heads and hearts of consumers to capacity with what their product is going to be able to do, and of course there is always some sort of letdown. The trick is hopefully the letdown doesn't cause people to go into a blind rage. It would appear the developers behind No Man's Sky are not as lucky.
They are currently under investigation for false advertising. Many many people were beyond excited for this game to come out, and then there was a couple of delays, and then it finally came out... The thing is that what came out wasn't what people paid for. You see it would appear that there wasn't just a couple of small changes, but large ones that consumers found misleading, hence the false advertising.
Consumers have sited the following discrepancies:
different type of combat than was promised
the different sizes of creatures
the way the ships are supposed to move
the different buildings that you can find in the game
The quality of graphics shown are not obtainable in game
Now I'm sure that there are a ton more issues, and I'm sure that some of them are definitely going to be around the promise of "a sprawling, procedurally generated adventure through the galaxy"