This is one of the great books in the general historiography of Canada. It was published in 1944 (which is glaringly apparent at times, more on that later) and posits the Laurentian thesis of Canadian History. Creighton begins with the establishment of New France and takes the reader through Canada's political and economic development, building largely on Harold Innis' staple thesis that tracks Canadian development along the lines of the main exports (fish, furs, timber, wheat, etc.). Creighton singles out the St. Lawrence as the main avenue of trade that shaped the development of Canada.
There are many aspects of this book that I really enjoyed. Creighton's grasp of the general flow of Canadian history is informative and impressive. His narrative is rarely interrupted by big jumps in time, and it is clear how events logically flow from one to the next. In particular, I found his coverage of the time period immediately following confederation to be engaging and well written. For readers with a shaky grasp of economics (what is a tariff, what is a customs union, etc.) Creighton does a good job generally explaining things without getting bogged down in the details. His coverage of how duties and areas of responsibility were split between the provinces and the Dominion (federal government) is particularly fascinating because it sheds light on the historical origins of the political issues of today.
There are plenty of valid critiques of this book, which is understandable given the length of time that has elapsed since it has been published. Creighton does a decent job of giving Indigenous groups agency in the pre-confederation fur trade era, he mentions them in passing during the settlement of the west and the establishment of the RNWMP (in a pretty paternalistic tone), and they are entirely absent from any parts of the book after roughly the 1880's. He also holds a pretty noble savage-esque view of French Canada that bleeds into the writing at times, which is dubious at best and is likely more an indication of Creighton's conservative leanings than anything. Finally, he virtually ignores the west outside the context of the wheat boom, which is understandable given the broad survey nature of the book and its focus on the St. Lawrence.
Now there are real issues with this book but I think there is absolutely a case to be made that it should be read by any student of Canadian History or anyone trying to get a better understanding of Canada's past. As long as you know the deficiencies going into it, the narrative that Creighton weaves is a very good overview of Canadian History (from a specific point of view). Understanding the political and economic history of the country is important because it illuminates the historical precedent for current issues (regionalism, health care disputes, relations with the US, etc.). This is a book that should be read, not because it is 100% correct, but because it talks about issues that are not really discussed as much in some modern histories that are more localized, in depth, and focused on specific lens of analysis. It is not the last Canadian history book you should read, but it could be argued that it should be the first.