Samurai Warriors promises and delivers much more than it's PSP predecessors.
The look of Samurai Warriors is kept almost completely intact in transfering from it's older brothers to it's younger counterpart. The menus (outside of a few options that the older brothers include, such as create a character) are almost the same. As well as the music, combat, and so on. You will find that Samurai Warriors has kept to the style Koei has given it.
The graphics of Samurai Warriors are a superior improvement from the older game. Not only does this title take full advantage of the wide screen, the characters are now much more crisp and detailed.
Sound wise you should expect nothing new. It's Samurai Warriors. All of the character voices and such have made their porting.
Koei has done a superb job with this aspect of the game. Now the "game board" levels move much more quickly, are much more interesting, and make the game more fun and challenging. Instead of having the same objective of lowering the morale bar to zero (like in the Dynasty Warriors PSP title) you now have random objectives every square. Some may be killing important leaders, others could be defending your supply captains. They are simple little things but they make the game that much more enjoyable. I was very saddened though that Koei decided to eliminate projectile attacks. Characters like Magoichi and Goemon are so much less fun now because of that.
Finally the lasting Appeal. If you are a fan of the samurai/dynasty series then I highly suggest you check out this title. The game style is very challenging and it keeps you in the middle of the Action as opposed to its predecessor. The game moves at a very fast pace, and when you are in a level there are no loading times.
You will also see unique level design that you didn't think they could pull off with this title, like the frozen lands from Samurai Extreme and inside giant temples/towers/etc...
The final thing I loved about this title was there the story was actually understandable!! Instead of some barely decipherable passage that floats by in 20 seconds you actually get first hand conversations from the main characters that set each level up. You also get little biographies of each character you so you understand who they are and what role they play in the warring states era.
Wrapping this up, if you were a fan of the previous "Warriors" titles I suggest you make this a part of your library. I've played State of War for a good 15 hours now and it's grown to become my favorite out of its two older brothers.