I've only played a couple of hours so far, and it's a good game.
But they really screwed up the hype this game had, and the good will gamers had towards it, with all the constant delays. And giving it away in a Humble Bundle, while still in early access, really soured backers that paid full price.
I did notice that the first few achievements I got, had a low rate. The first achievement in the game only has a 15% rate. Meaning that even the people that already bought the game, are not playing it.
Although the game was eventually released, it has become a good example of why early access can go very wrong.