The promises the game devs make are large. The trailer posted today looked great. Grappling hooks as infinite use offhand item? Awesome. The lack of space flight seems to be a missing factor. I like that the universe is shared. I was concerned with No Man's Sky being such a lonely experience. Minecraft did well partly because it had a social element.
steam early access reviews even just a week old are not that positive.
Modding this (other than UI probably) won't be possible as it's an MMO.
The current early access price tags are kinda high.