Here are my impressions:
Perspective seems to be working really well on your larger shapes, the second image especially. I like how use added shading in perspective as well. Shows you have a good sense for how things are really working, rather than simply applying rules.
So, all that's left is nit picking. In the top image, there's an object in the distance on the right, a bit up the hill-- a water tower? It looks a bit off to me. Maybe try drawing it as a box on top of a box, paying close attention to centering the top one (draw your x's, etc), then fill in with cylinders and see if that helps.
For the third exercise, I think the larger/closer building looks great. Your additions of architectural details, clothes line, etc, seem to be working well. The open door looks askew to me, not sure if that was intentional. The second building looks wonky to me, and I'm guessing that's just because your vanishing points are so close in.
Maile