It is fine in solo mode, as others have said take your time to progress, don't let the graphics fool you, they have a beauty that is hard to appreciate until you actually play it.

I ignored this for months, just on the strength of the store page video's, even though it has great reviews. Then I watched some early game lets plays a couple of weeks ago, to get a feel for it, still I was undecided. Then I took a chance and got the game.

It is very relaxing, and can get manic and out of control if you choose to push too far too early in game, I love the freedom it gives you, the sea and weather is top notch atmospheric (don't forget to bring your sea sickness tablets :-)

As for npc's, it would be great if they add more in the future, I would be surprised if they did not, given how early it is in development

While not npc team mates as such, there are several things you can tame, one of which can be companion or two or 3 or.... , with out spoiling too much, I will leave it there !

Do your research, this game won't be everyone's cup of tea, but I love it so far, and I can see myself putting in plenty of time toward building, construction and exploration, in the future.