I like your style. For a build made of found items, you have a nice mix. The smoke stack might drip, like Dave said. You could either catch the drip, divert it, or rework the stack to prevent it... But the stack adds to the charm of the build. So does the friggin door latch, I bout fell out of my chair when I saw the first pic of that... Nice touch! This smoker is very over built, but in really good ways... Let's 'em know you are serious about your smokin'. The fridge was not too nice... the smoker is too nice.
I like the 2" chip pipe, though I might have tried to do a larger one. But if you are sticking with found items, you might be limited there.
The only thing I would do that you probably won't is add a computer controller with a bunch of temperature probes, and a computer controlled blower/igniter for the smoke injector. But that is just because I'm an engineer, and putting computers into things is what I do... We all have our vices. The main reason I would put a computer in it would be so that I can keep an eye on it while I go to the store to buy beer, or so I can brag about what's for dinner while I'm at work (my co-workers range from computerized green-egg users, to home brewers, so there is a lot of home automation competition).
And when I say "computer controller" I mean a computer that not only controls everything, but that serves up a web page that can be displayed on the TV, and on my smartphone, so I can take my controls with me wherever I go. "Yeah, my bbq pit is on the Internet..."