Well, rotting is the most obvious that applies to any and all limbs, but some rot more frequently than others, and the rust of the limb can also vary depending on your job. So take Nikolai, he’s got his metal hand, yeah? Well, because he’s around steam-leaks so often that hand of his is a big inconvenience since the water from the leak rusts the hand pretty quickly. Now if someone were to have a metal hand and be working on the Farm just digging up potatoes and the like it wouldn’t matter much, since there wouldn’t be a lot of corrosive materials around to speed up the rusting process.
I’ve already covered pretty much all of the drawbacks on the torso.
Legs and Arms can stiffen up if not oiled frequently, which can be deadly if pipe-crawling. Imagine you’re trying to make that leap, and your leg stiffens up so instead of jumping you just fall like a rock into the depths of the wall? Not exactly my definition of a fun time. They also need to be replaced as often if not more often than the torso- of course with less deadly consequences if ignored but if you have the arm of a five-year-old on a fifteen-year-olds body then that’d probably irritate the skin. Also- skin is can be a big problem.
Nowadays when someone needs a prosthetic arm or leg they (most people) have a “sock” that they’ll put over what was left of the limb, and the limb itself was probably sewn up and treated before they even received a prosthetic to begin with. (All this is knowledge from research I did when writing a story that involved one of the main characters having a missing limb, so it could be horribly wrong and/or misinformed, but it’s what I found from my own research.) But, as said before, medical technology isn’t exactly modern, so there is no real “sock” save for some thin cloth or balled up cotton, and the skin is already irritated and probably didn’t heal 100% correctly. This can cause for irritation, bleeding, swelling- and, most dangerous, infections. People with metal arms or legs have to watch out for infections if the metal tears through the thin cloth and then cuts up their skin. Any tiny cut needs to be cleaned as soon as possible and then treated as best they can. (Did you know there was a poet who died when he pricked his thumb on a rose thorn, and the cut got infected? Ironically poetic, but also a reminder that even the tiniest cuts can be deadly.)
The Face’s main problems come from the eye and replacing it, and applying it in the first place. It has to be replaced ASAP like the torso, because otherwise you risk having it crush your skull. Applying it in the first place is near impossible, and half the time those that require facial prosthetics are on the verge of death (like the torso) to begin with. Also skin it’s not detachable like the arm or leg, the skin can grow over the face. That’s… not good. It hides any rust, speeds up rust, and is prone to infection. It’s like when you leave an earring in for too long, the skin grows over the earring and you have to cut it out of your ear, lots of blood and pain (an experience I know all too well…) The facial prosthetic owner has to be wary of this… but there’s really no way to prevent it? Other than scraping off your skin whenever it gets too close, that is.
The second major problem in the face is the eye, which is basically a glass eye… mostly just cosmetic, but as City technology gets better more and more goes into developing a way for the eye to actually see and be hooked up to the brain. Right now, someone with a facial prosthetic might be able to see vaguely fuzzy, nearly colorless forms with their prosthetic eye (assuming vision in the other eye is fine, then they’d still be able to see out of their other eye normally). But having poor sight is bad in such working conditions, it makes it hard to move and do certain tasks, especially those that require precision, like repairing the smallest gears.
As stated above it depends on what you’re working in and the quality of your limb. Some people go several years without ever worrying about their limb rotting because their job doesn’t really put them in any danger. Some people with arms or legs see their hand or foot rot and (assuming the rest of the leg/arm is also metal) don’t have to worry about it yet because it hasn’t even gone near their skin.
No, rotting is natural (all metal rusts, after all), and it’s part of the City’s job to replace a rusted limb. Nobody really knows what the City does with the ruined metal- but they assume it reuses it somehow.
No, and it’s never really “revoked” it (that anyone knows of). It’s… hard to get in the City’s bad side. You have to be actively trying to either ignore the City or going against its wishes (I mean look at the current playthrough, if you want the City to hate you, you really have to avoid it at all costs and be as rude as possible to it.)
[spoiler]Now, to say that it hasn’t “taken care of” those it identifies to be a threat to its Children, or even just itself… well, that would be false.
Also, why would The City give up the chance to have someone under its thumb, as its Child, if they so displeased it? It’d be much more helpful to make sure that they can never disobey the City again…[/spoiler]
Nobody has ever left the City that anyone knows of.
Where would they go?
If you’ve ever been in a cave without any light (I have, it’s creepy), it’s pitch black.
I mean Pitch. Black.
You can’t see what’s in front of you, you can’t see what’s beside you, you can’t even see your own hand if its in front of your face.
That’s what lies beyond the City, thats the Underground.
This is great reasoning. I had a feeling the arm would be the most popular!
but,i still like them with their rule and restriction and hey they are our MC savior anyway or are they?
i like her too…but 
and strong…
