Bleh I read a couple classes in that guide, mostly just general advice, and it has typos too, like it says that the sniper class has one of the lowest health and because of that they are "unusually hard to kill."
I wanted to read tips like the spy killing SG and engie at same time tip (theres a video on youtube, you backstab the engie and quickly switch to sapper to sap sg before it can turn around and kill you).
In other words, this is a guide for n00bs, not for experianced players.