Is it worth playing now or would it be best to wait and see when it released in full?

It's merciless and frustrating. It is abrupt and arbitrary. It is nonetheless fair and comprehensible. It's pretty much exactly what fans of the roguelike want. As is often the case, I think Penny Arcade summed it up quite well.

If you like roguelikes, spend your money on it.

EDIT: typo

SECOND EDIT: I should probably go into more detail? Fine. The art is a bleak and striking affair, very much reminiscent of the cutscene art in Witcher 2 if you remember that. The game doesn't do a terribly good job of explaining some things (like when you set out on a dungeon and get to the "provision" screen, there's really nothing to tell you that any excess stuff you buy is wasted; nothing can carry over to the next mission; or when you send one of your heroes to the Inn or Church there's no real indicator of how much stress relief they will get) so there's some "learn by dying" involved. And some things are outright mean, though when they happen it's always obvious that you could have done something to stop it. For example, you might not know that if your stress bar ever hits 200, your hero will have a heart attack and die, right on the spot. So you might be slogging through a longer dungeon, trying to wait until the optimum time to rest - or just trying to finish the thing - and suddenly be attacked by a caster with the irritating ability to increase stress by ~20 per cast. Bam. One of your more emotionally-fraught heroes dies, your group is down to three, and your chances of surviving the dungeon have just turned very bleak indeed.

the game is pretty good as it is. Nice gameplay, very good mood, quite beautiful graphics. But I would recommend to wait for release, as it feels a little "empty" right now. Plenty of stuff to do, but I don't feel I'm getting anywhere. But when it is complete, it should be pretty awesome :)

Quickly burnt out on it within a week, after an all too early point where the levels keep rising but the content ends. I'm certain I’ll never go back and have tainted what would've been a better experience had I waited for the full release.

My advice is to avoid Early Access and fill your time with one of the thousands of complete games on the market. Then again some developers need that cash injection from Early Access to finish the game in the first place.

sorted

http://www.penny-arcade.com/news/post/2015/06/03/asymmetry

It's worth playing now if it was a 10 dollar game, i.e. it works, it's just rather short and shallow.

The asking price is 20 dollars last time I checked and it's just not worth that, sooo I'd recommend waiting until it is released. It looks promising and it could have been released already at perhaps half price.

Dark

It ruined me for other games.
Once you go darkest, you don't go back.

I really hope this comes to GOG, been wanting this since it was released in Early Access. I agree, the $20 price tag (even $15 on sale right now) is a bit steep.

Oh, the 20$ price is probably good... For the complete game. Right now, the gameplay "frame" is quite good, the graphics and texts are very neat, but it's too light on content to hold my attention very long. When (and IF) it will be finished with a little more stuff to aim for mid-to-late game (beyond "redo the dungeon, but harder), then it will be quite worth it.

http://www.darkestdungeon.com/topic/darkest-dungeon-full-release-date-january-19-2016/

Pretty dark, and a bit dungeon-like.

Do you know if they improved and expanded it?
The game seemed good, but also too unforgiving (=grindy) and a bit limited (few dungeons types in the map).

Here is an interesting blog post from Jeff Vogel (Spiderweb Software) where he talks about difficulty creep in Early Access titles, taking Darkest Dungeon as an example. But the developer seems to have noticed the problem and is dealing with it.

Early Access, Difficulty Fetishists, and Driving Yourself Insane

Yep, interesting article.
The comments are full of spam though XD