Robert Paul Weston is a bit of an oddity, at least in terms of classifications. He was born in England, though was raised in Ontario. He also received an MFA from UBC, then promptly decamped back for England. As far as I can tell, he did write much (most?) of Zorgamazoo while at UBC, so I shall count this book for the Canadian Challenge, but not any of his subsequent books (4 so far).
I'd say the book comes across as a fusion of Edward Gorey (a bit forgotten nowadays), particularly in the quasi-gothic ink illustrations throughout the book, and a bit of Lemony Snicket in the plotting. There might even be a bit of Neil Gaiman's Neverwhere in the mix.
The single most notable thing about the book is that it is written entirely in rhymed couplets. For the most part, the reader just jumps into the story and it is noticeable but not completely distracting. There are some moments where the rhymes get so outrageous that they recall some from Byron's Don Juan. But this is part of the fun. Another aspect that occasionally draws attention to itself is the typography and design. Occasionally the words get smaller and spiral inwards, or they get twisted around. A few words are scribbled like graffiti and other words are in an Olde English font.
The story is a fairly basic quest. Katrina Katrell needs to escape from her truly terrible governess, and she is saved by the bumbling Zorgle, Morty. (Zorgles are something like talking bears but with horns on their heads.) Katrina is a rash adventurer-type, whereas Morty is risk-averse, though he is the one tasked with finding the missing Zorgles of Zorgamazoo. As much as he wants to decline this quest, he decides he needs to at least try, to make his old man happy (his father was a famous adventurer). Needless to say, the two form a pair that are greater than the sum of their parts.
The story zips along pretty quickly. It valorizes having a good imagination and being true to one's friends. All quite acceptable in children's lit. It even has a lesson that may be a bit too subtle, in that sometimes one can use a bit of jujitsu on an adversary and convert them so that your interests are aligned. Other enemies are just bad through and through, and they can be squashed (like the aunts in James and the Giant Peach). Obviously, knowing the difference is important. Saying too much more would probably spoil the fun.
This book is aimed at children from roughly 8-12, but older children might be entertained. However, it is more likely that teens would just not find the book cool enough for their taste, and they might have to wait until adulthood until they might find is acceptable to read and enjoy it for the cleverness that imbues this book.