You gave me a lot to think about! I've taken the time to edit each and every part you've critiqued, so I want to thank you bunches; it's helped me not only in the short term but in the long term for future reference.
As for this part:
"The one thing I'm a little unclear on is what POV this is supposed to be - it feels entirely centred on Will, but perhaps gives a few too many 'outside' statements to read as close third person. I think, if you want to take this angle, you should play up your sarcy narrator, it really fits very, very well."
This is something I can't deliver a quick fix for at the moment, but it's something I can definitely work on later. Perspective could be one of my weak points. I've had trouble in the past deciding on tone choices for narration.
I really liked yours by the way! Your writing is dense with descriptive flourish. I felt like I was reading the equivalent of a painting. It's a style that kept me entranced all the way through. I loved the compare and contrast the main character does between what was once a beautiful pastoral world to one which had been overtaken by cold industry, a theme spiced throughout. I especially fell in love with the way you compared the innocence of rain in the time of one's curious childhood to the melancholic fever of rain in the putrid city as an adult. The existential paragraph where he thought himself a fly buzzing around aimlessly until death was chilling.
The sexual nature of the following scene was done very well. Normally I'm not a fan of a story going into that kind of stuff immediately, but you managed it awesomely. It added an interesting angle of depth to the "monkey trapped in a cage" crisis Casper was going through in the city, wherein animals in captivity tend to try to enjoy themselves more often, that his state of mind was at least partly a result of the terrible environment he lived in - his state of mind then leading to more tragedy (lost job). It was like a feedback loop of failure between himself and his environment.
The last line of your work was well-placed, it grabbed me immediately and told me to read more. The contrast between his negative perspective with the sudden anticipation he felt - someone golden was approaching.
The only roadbumps I found were these:
"waxing philosophic with" : I had never heard this expression before, and so I was unimmersed from the story for a brief moment to think about it.
The screeching taxi line was a bit long; maybe break it into two sentences or shorten it.
"exertion" : For me, this word holds a technical-writing feeling to it, so it felt out of place seeing it in a sentence where he was experiencing a very personal bout of nausea.
"Message from the gods that." : This one confused me, I wondered at first if this was an error of my own comprehension or a deliberate break.
Very good work, I loved it!