I have a 2013 end macbook with an Intel Iris GPU.
I was wondering whether any of you can comment on the game's performance on a similar setup - as I'm hesitating between getting this, a PC or the PS4 version.
For the record I don't mind modest (but not ugly) graphics without the fanciest special effects as long as the framerate is okay (~30).

The initial scene of the game appears playable (tho at sluggish framerates) on an old AMD E-450 APU (CPU with AMD HD6320 integrated graphics) with 4GB of RAM. Intro movies are almost completely dropped (but no in-game movies have yet been seen while in the first town/area).

Something with a little more horsepower than an E-450 seems like it could handle the game. As for video, try finding a 1080p .webm video somewhere online and see if your system can play it in a browser without dropping all the frames.

I just tested the character creation & tutorial and first area of the game on a 2015 fanless mini PC with i7-5500U.

The game was entirely playable (with AA, vsync, and dynamic cloth disabled) at 1920x1200, mostly thanks to the mouse cursor remaining highly responsive even when the rest of the screen updates slower. Yes, the rest were quite slow to render. I didn't see a framerate counter anywhere, but something like 20 fps would be my first guess. Dropping the resolution to 720p made it all more than smooth enough, at the expense of obviously degraded visual quality. (Made worse by the fact that the game does not retain the aspect ratio, unfortunately).

I don't know whether these areas are representative of the rest of the game, but I'd say it's totally playable, and yet suboptimal, unless you're ok with dropping the resolution.

As far as I understand, the Iris GPUs should be a bit faster than the one integrated in my 5500U. But I can't tell by how much. If my 20fps guesstimate is right, then the Iris' extra performance along with a slightly lowered resolution (1920x1080 maybe?) could very well be enough to take it the 30 frames per second you're aiming for. There is one way to find out.

Thank you all for the replies. I'll wait a bit for performance patches and a bit of more feedback before buying the game, but I'm optimistic :)

First planned patch is said to focus on performances, so hopefully you won’t have to wait too long ;-)

I've got it running on an Dell Latitude e6230 mobile Dual Core i5 with Intel Integrated HD 4000.
It is rather sluggish at times which makes it little fun to play. Audio is interrupted often and it crashes very often on scene loading / initial startup. I hope future updates will make it more performant - I see no reason as to why performance is so bad.
I know I do not meet the minimum requirements. I was a kickstarter backer and got a code for the game - otherwise I wouldn't have bought it.
My guess is however that on an Intel Iris and desktop CPU the game should run with a good frame rate.