Yes, it is definitely not anywhere near complete, although it is possible to get a lot of time out of it if you wanted; there's just not much variety in it yet. I think it looks like an awesome game, and I tried it out, but it's too scary for me.
I might buy it soon, but I don't know if I'd play it much until multiplayer is added to it, because I know that playing a horror game with other people is not (as) scary for me, and a lot more fun. And I think it'd be a lot of fun trying to survive together.
For example, the Left 4 Dead single-player campaign was too scary for me to play on my own, but I had no problems at all when playing co-op. 