I'm going to break this review into two parts. One covering the Stalker itself and one covering the non-stalker specific content.
First the stalker: I've mixed feelings about the stalker. This first class in the path of war series feels far less iconic than the original Tome of Battle classes. I had a clear concept of what a sword saint was thematically while I feel the stalker is more just an amalgamation of abilities. It is clear the stalker is supposed to be some sort of fighter/rogue or assassin type but we've already got a lot of those and the stalker does little to stand out thematically. Mechanics aside there seems to be almost no difference between a rogue and a stalker and I always consider that to a negative with a new class.
Like their 3.5 predecessors the stalker enjoys a healthy mix of class abilities and martial abilities which is good as it help these classes stand out from each other. While I applaud Dreamscarred for thinking outside the box a little with these class abilities and not just giving the usual remix of other class feature, I must confess I found them to be a little hit or miss. For example the passive Deadly Strike, which leave victims of critical hits open to extra damage, isn't something I've seen before, but isn't very interesting. Fortunately, like many pathfinder classes, the stalker has "stalker arts" which allow for some customization of the class and those offer some nice options which will help mold your stalker.
So in short their is nothing wrong with the stalker, if you want a sneaky assassin type, but honestly you could have just made the stalker an alternate rogue package where they trade in some stalker arts for Techniques and stances.
Part II: The other content
I'm happy to report the feats included in this book are excellent and a real high point for the path of war. While some are better than others none of them feel like duds nor do any seem over powers. I particularly enjoyed the martial training feats allowing single class characters to pick up a few path of war techniques and stances. These are the best feats since the amateur gunslinger feats for allowing other classes to dabble in other classes. I wish ever class had well balanced feats like this to allow people to add a little crossclass flavor without level dipping.
The new martial system is very much similar to the 3.5 one and that is a mixed bag. The Tome of battle was one of the last 3.5 books and was rather rushed which is evident by great ideas but a clear lack of editing and play testing. If Path of War has a flaw it is that it follows them a little too closely in some parts. A few entries are not as clear as they could be and some powers particularly at the higher levels feature very 3.5 mechanics like save or die which I'm not a fan of.
Since Dreamscarred couldn't use the original fighting styles from the Tome of Battle they've had to make all new classes and have taken the opportunity to shake up some of the old ones as well as adding in all new ones. Broken blade is the most martial arts like and my current favorite, while solar wind goes into much welcome new territory by being a non-melee style, steel serpent becomes the new assassin style, thrashing dragon the new two handed style and finally veiled moon takes all the teleport moves which in tome of battle were bundled into the assassin style and expands them into a nightcrawler/shinobi like teleportation oriented fighting style.
One element I really enjoyed about these new styles was the attempt to add more utility to these styles while also exploring ways to keep them from being abused, something of a problem with the original fighting styles. Most of course are still all about either just dealing extra damage or avoiding damage but there are a few items here and their that show their is potential for the path of war classes to be well rounded without being broken. I'm sad to say however that at 9th level each fighting style leads to only a single typically save of die super move which isn't something I enjoyed about the original fighting styles and I like it no better with these new ones. I hope before we see "Ultimate War" that Dreamscarred finds a way to really round and these fighting styles and fix up a few of the techniques.
In the end the Stalker isn't a bad start to the path of war, but neither does it fully live up to its potential and correct all the issues from the Tome of Battle. If you enjoyed tome of battle and could look past it flaws than you simply must buy Path of War there is much fun to be had here, however I must confess this isn't nearly as polished or refined as Ultimate Psionics at least not at the time of this review.
[4 of 5 Stars!]