This is going to be rambly, I'm sure.
Vernon said, paraphrased, "No book will reward the dedicated student more, or the casual reader less" about EATCT. I agree to an extent. This is a book that has to be studied, not just perused. I read it cover to cover twice before I even studied any sleights with cards in hand. Because I had a feel for how he/they wrote, it was easier to understand what they meant in specific descriptions.
But I also think times have moved on and the book isn't necessarily the revolutionary gem it may have been at one time. Techniques have advanced, playing cards have advanced. If I were to label something as the best source for a foundation in card magic today, I'd say Card College. That being said, I'm not focused on cards these days and I haven't been for years.
The reason I think every serious card worker should read and study this book is because it shows the genesis of so much of what's on the market today. You study this book and say, "Oh, that looks like XYZ I just saw released on a download."
I think two big things influenced the writing style of EATCT (And these are purely speculation, I have no data to back it up): 1) That was kind of the style of writing for magic books at that time. Other books I've read from that period have similar styles. 2) I think Erdnase was trying to sound more educated and eloquent than they actually were.