I feel like the rules are poorly explained and I had trouble using them. There are also lots of spelling mistakes that can make some of the information harder to parse. There are some good tools in there, but I was disappointed overall.

As a fan-made improvement of Warhammer Fantasy Roleplay 2nd Edition, Zweihänder blows its predecessor out of the water with customization options, setting agnosticism and smart new game mechanics such as peril to represent the physical and mental exhaustion of your characters. While the game's presentation could use a little work, the book being over 600 pages making it difficult to find the rule you need when you really need it, the game itself is amazing, offering a lot more freedom to players and GMs. Grab this while you wait for WFRP 4th Edition. You won't regret it.

This book adds a lot of options to the character creation for KAP 5.X, which makes it a must-buy for whoever wants to play as knights that aren't Cymric. Since it will almost only be used during character creation, I recommend buying the PDF rather than the hardcover.