I noticed that this got an update, and I DID scan it thoroughly before putting this up.
This review isn't going to be elegant, but it is going to be from a player's perspective of the material.
The setting information is great. It stays with the vibe the original 3.0 version had and I feel that the update, while a name change here and there, is overall phenomenal. The amount of work on JUST that by itself is amazing. There's nothing I can bash here.
I'm going to just come right out and say it. Kensai. The hell happened to Kensai?! I see that, after going over the class, that the goal must of been wux fu of some sort, and I do not dislike that at all. But some things just aren't meshing well with the concept, or so I feel. The bonded weapon is standard fare that Eldritch Knights can play with, so nothing too rediculous there. The Cha focus over the expected WIS is to not step on the Monk's toes, though honestly DEX/CHA feels like BARD and I personally felt that STR/CHA would of been a better fit, and it still manages to step on the Monk's toes by having a Ki system ANYWAY. The problem comes when you compare the first archtype against everything else about the class. That first archtype feels honestly not needed. Its that gimped. Its supposed to be a blade master, right? Where's the mastery of the blade? It gets a choice of two fighter styles, which gives the illusion of being versatile in approach, but in reality its just a token gesture when the others get either exact, or better. Its archtype ability, Blink Strike, drains on its already limited resources, while its other archtypes either don't (looking at you Unseen), or is probably far more long lasting ( I see you Stances).
Honestly I think that's what really holding me up from liking that archtype. It wants so hard to be that epic anime/ wux fu one against many fighter... but it fails. It doesn't even obtain that ability til level 6, while its other archtypes have either been blurring, super hiding, or been shrugging off low level fear tactics since day one. That's a bit... underwhelming. In the group I played in, when the class was on the table, Blade Master just couldn't compare to every other archtype Kensai has. Unseen Hand is fun, combat blur, telekinesis and the Weave is just a few (!) of the things that make the archtype great. Shinobi follows suit as a less gather intel and more of a in the movies ninja, which captures the feel for its goal rather well I think. Samurai felt.... off. I personally felt that most of it could of been rolled into a fighter archtype instead, with the better chasis and result, or even the Shogun (!!) but it was still better than Blade Master ( seriously). The Ravager is nuts. But the low hp of the class compared to other melee fighters balances out its stronger points extremely well. Its ability to regain Ki is a bit late, but it does get better pretty quickly so not a downside. The manuevers aren't game breaking, and honestly, some of the fighter's is outright better than most of it. The stances are a sweet touch that nods to Tome of Battle. But I keep coming back to the oh so gimped Blade Master. It does NOTHING unique till level 6, which, by that point, EVERYONE is starting to come into their own: the blademaster just started. It gains a form of fear protection.... at level 15...okay... sure, let's just ignore the save or dies flying around and focus on not being scared. The lvl 18 ability feels... just in general weak. Maximized die... for one hit... per day.. not worth hitting 18 for it. and the last ability, yes, last, at 10 is... bonus AC... when in melee. That scales with number of combatants near you... which means you STILL aren't AC tanking.
Overall the book is good. The feats are generally from bad to meh, but that's not a terrible thing. The new spells and base class options are fun, and not too overwhelming (except fighter. ALL of his new options make blade master look as pitiful as I stated it to be.). Pristine/Masterwork stacking (or +1 damage from Pristine and +1 to hit from masterwork) WOULD be a problem... if custom magic item rules existed. As it stands, since that its FIRMLY in DM domain this time around (and with the high end on weapons being +3), they aren't TOO terribly unbalanced. The book has flavor, and outside of the poo taste of Blademaster, is rather succulent.
Again, this is my two cents. The player that tried the Blade Master took it to 12, then let it walk off a cliff. Take that what you will.