Since the first one has devolved into a discussion about tournaments, like every other ****ing thread, let's start a new one JUST ABOUT KNIGHTS.
I don't think they fit into the game at all, at least not as an army. They would be just fine as an addition to another imperial army in a LoW slot, but an entire army of scoring, AV13 titans? Even Fox news is more fair and balanced. Every anti-infantry weapon you bring (which you need to deal with all the other armies out there) is now completely ****ing useless. Want to get into close combat? Better have Power fists or melta bombs, because even krak grenades are worthless.
Your infantry will get shot then stomped, monstrous creatures will get the D in their face... I don't see how any force could be built to have a reasonable chance of winning vs this list while still having enough anti-infantry weaponry to take on a green tide.
On that note, how the **** could Tyranids possibly beat an army of Knights? We have no guns (except the tyrannofex one that no one takes) that stand even a remote chance of hurting one of these. IF you get into combat, they will tear monstrous creatures and infantry apart with equal ease, and they're faster than you, so they can dance away every turn as they blast you to pieces. Crone spam is the only thing that could reliably do some damage...
40k has always been about my army mans vs your army mans with a few cool big toys on each side. Pretty much all armies follow a basic formula, with only a few outliers here or there. The necessity to take regular dudes as scoring units to win in most scenarios has forced people to build certain types of armies, so you at least have a rough idea of what you will be up against. This book is going to throw all the logic and normalcy out the ****ing window.