Very cool! The scene's overall impact could be greatly increased with more adventurous lighting, though. And why not more blues to convey a cold wintery feel outside, so the warm inner glow of the secret hobo lair is made to look even better, like a real haven from the cold for bums.
And now I will totally desecrate your pixels in order to better convey what I'm talking about, prepare for phoshop butchery
look away!
The edit takes care of the tragic lack of contrast and plains of monotonous texture. Only made it because I love the scene, yet know it's full potential is far from acheived. Not a suggestion of an easy revision I realize, but it's hopefully helpful anyway. Oh, and I don't really detect any perspective problems, but those plain old stones do bug me, though they do balance the scene well. Gotta like your strong symmetry.
Finally, the gate doesn't look like a bum's hideout, it's too clean and perfect. It needs odd homeless people paraphanelia laying around, nailed to the wood, graffiti, etc. Grunge it up, sir peach.