Read over the knight right after I got the book. I think it's pretty good, but I do have two issues with it:
1. For a class that is all about defense, and even has class features that work with shields, they should have Tower Shield proficientcy right off the bat.
2. It uses CR as part of mechanic. While it's not as bad as the Truename stuff in Tome of Magic, it is annoying in that CR is a bit imprecise anyway, and it falls into the same trap as polymorph, i.e. every creature needs to be complete vetted to work against this ability. If it can't be done with a core ability, it certainly can't be expected of one that's in an optional book.
Otherwise, I think it's a cool class. Lots of the problems that people have with it flavorwise are eliminated if you consider that a limited amount of cross-class selection will allow for those abilities.
Raymond