In the most recent update they've brought in the ability to fortify windows and such so now you can have a base with power and water that's fully shielded with boarded windows. You can protect the doors with locks and use shotgun traps and flame traps to cover the doors. It's pretty playable at the moment and theres an update coming hopefully on the 23rd that you can look at in the changelog. https://changelog.survivethenights.net/
What are you expecting to get here @Wootah ? From a small team with limited funding were you expecting an AAA title out of the box? Or like most of us, were you expecting a running work in progress you could help turn in to the best zombie survival game ever? As @LonelyBeaver rightly says, the improvements just keep coming.
To answer your question as to playability, well I'd have to say yes.
There making huge progress but I will wait another year or so. Ive been here a long time already and backed them from the start so im willing to wait for the game. What ive seen over the years is epic and I'm glad to see it still move at a high rate. I think its totally playable but Im not going to play. not till its complete, as i dont like Alpha testing anymore with any game.