If you've not read any of the Mercury books previously, this is not the place to start, though chronologically it is. Perverse I know, but then so is life sometimes, as you'll know if you've read the series!
So, if you've not already, I'd recommend you at least read book 1 of the trilogy first: Mercury Falls (Book One of the Mercury Series)
This (very) short story fills in some of the background to the Mercury story in the trilogy, and as such, is probably better for being in on some of the jokes contained therein. I suspect it wouldn't be anything like as funny if you came to this first.
It is very short, so even at the low price currently listed, arguably not the best of value, but if you're a prime member you can borrow it free, and hey, it is only 77p (currently), less than half a pint. If you go to a cheaper pub than usual you could buy this and enjoy it with a pint at no added cost. That's not a bad idea.
So, in short, recommended if you enjoyed the trilogy, not if you've not read them, and obviously not if you read them and hated them, that would just be silly.