Rikimaru and Ayame: They both rock, and Ayame's a cutie that will slit your throat at a moment's notice. Each has a different story, even though the areas are the same. Also cool about Ayame: Actually is from a natural looking woman mold and not the Mai Shiranuai "Me Bouncy!" look.
The levels: Long and winding enough, but the perfect difficulty to get through. Plus, each level has three scenarios to get through with different placement for enemies, so the replayability is high.
The weapons: The grappling hook is your friend. The poison rice ball is your friend. The steel bear trap is funny.
The kills: Nothing better than decaps that look like you're poppin' a zit.
What didn't work:
The bosses: *WAY* too easy. I mean, as long as you know how to block, have enough energy sake, and hand-eye coordination, you'll get through.
The camera: It's ok, but could have been a bit better.
As for the "Meat," it seems like every other expansion has made a significant change to the gameplay or player options. Burning Crusade: New zone, flying mounts, two new races, Horde Paladins, Alliance Shaman, the new continent, 10 levels.