Subject says it all. I saw a couple of complaints about the dungeons being too dark. Also noted that the users mentioned that they are using retina MacBooks like me. Didn't understand why my dungeons seemed nearly completely black until I saw my SO's screen as she played sitting right next to me on her MacBook Air and the problem jumped right out at me. My MacBook w/ retina screen is clearly not rendering the dynamic lighting at all. Since the lighting in several of the dungeons consists primarily of dynamic lighting, those of us on MacBook retinas are playing those dungeons in almost complete darkness.
Problem did not go away when connected to an external monitor nor when disabling "Automatic graphics switching" in MacOS' "Energy Saver" preferences. Full-screen, windowed, faked full-screen makes no difference. Tried fiddling with all the settings in Divinity's graphics options to no avail. Nothing turns the dynamic lighting on for me. If I could post a screen shot on the forum, I would.
Larian, I'm a senior software dev (20 years in the industry) and can send you screen shots and troubleshoot the problem with you if necessary. Feel free to contact me via my email associated with this account and I'll assist however I can.