I am considering buying the game. I didn't think much about specs because I figured a 2D game would run fine. However, I have an i3 and a Geforce GT 740m and reading the specs on the GOG website even recommends a GeForce GTX 660. Did anyone here try the game on a weak-ish rig? Can anyone tell if the specs on the website are inflated, or is the game relatively demanding after all?

Reading about some of the troubles of the developers on the steam forums suggests to me that I maybe shouldn't hope for stellar optimization?

You might have better luck posting the question directly in the game forum: https://www.gog.com/forum/darkwood. Since the game is new on gog, forum should be active and might even be under watch by developers.