If you enjoy the Dynasty/Samurai Warriors games at all, Samurai Warriors 2 is simply the best in the series.
Let's start with a few things that the official review conveniently left out. To begin with, the game changes up mass combat by dividing characters into three groups: Normal, Charge, and Special. Normal characters fight mostly with the regular attack button, switching it up with the occasional charge attack for simple, effective combos. They play the most like what you're used to in the other games. Charge characters have fewer attacks, but are able to use their Charge attacks multiple times in a combo, often achieving different effects. Finally, Special characters are a bit limited in straightforward combat, but can use their special abilities (another new addition to the series) to achieve affects beyond those of less-specialized characters.
Secondly, the story is by far the best-translated and performed one we've yet received. Cutscenes and in-battle commentary give you a real taste of these characters' personalities, and generally serve to make you like and even care about them. I never thought I'd say this about a Warriors game, but I actually teared up a bit during one of the storylines -- yes, I'm a softy, but it's still shows the game's surprising emotional impact. Even characters that would in most Warriors games be incredibly annoying, like Hideyoshi Toyotomi's cheerful wife Nene, are so excellently written and performed that you can't help but love them.
Thirdly, the skill and item systems have been changed fairly dramatically from the Warriors norm. Instead of equipping a limited number of items to give bonuses like boosted stats or the ability to ignore arrows, characters learn Skills by gaining experience and defeating enemy officers. Any (or none) of these abilities can be equipped at any time, but the most powerful can only be obtained by obtaining every other skill on a character's list, and then battling in specific maps against officers who know these abilities already. In addition, each character has a unique skill that allows abilities like double-jumping or ignoring damage while one's Musou bar is full.
There are, admittedly, two major weak spots: the minigames, Suguroku and Survival. Suguroku is a board game, sort of a hybrid of Monopoly and Chutes and Ladders, and winning at least one game is required to unlock one of the game's characters. Simply put, it sucks. A lot. Survival mode is a bit more fun, as it's based around the core gameplay of hitting bad guys until they die. You progress through an infinitely tall castle, completing missions for various characters and unlocking things along the way, like Ranmaru Mori the transgendered swordsman, and the two unique, powerful bodyguards. Unfortunately, it quickly gets very, very boring and repetetive, and if you choose the wrong mission path, you'll be unable to recruit the characters and will have to start over from the beginning.
Aside from this, though, Samurai Warriors 2 is a very solid, enjoyable hack-and-slash of epic proportions. With its interesting and likeable characters, unique character progression, and variety in combat and movesets, I feel it is by far the best game in the series. Enjoy it, Warriors fans!