I believe the lighting is believable, the sunlight being the main source, and several smaller sources making up for the rest. Though probably slightly on the light side, I think it's not that unrealistic. I had considered putting way more eyecandy in like loose bricks and all that for a really long time too, even tried it in a lot of spots, but it simply made my intended minimalist style ideas go to waste IMO.
I'll agree that it could've been detailed a lot more, but I was going for a really sober looking project, and I think I established that well.