Here's word:

Honed by years of relentless training and tempered in the fires of battle, these nine elite warrior units excel in their fields, and stand head-and-shoulders above their rank-and-file brothers.

The units:

Kiyomasa's Katana Cavalry - these heavily-armoured cavalry units wield their blades with a brutal expertise.
Yoritomo's Yabusame Cavalry (bow experts) - precise and quick, these men can snipe at enemies, and hold their own if cornered.
The Spears of Shizugatake (Yari cavalry) - masters of the spear, these expert horsemen boast a devastating charge, and resolute morale in the face of counter-attack. Flank and strike with these spear-wielding cavalrymen.
Benkei's Blades - the long-bladed Naginata is effective against all-comers – doubly so in the hands of an expert.
Gozen's Hime Heroines - in the hands of a great heroine, the Naginata becomes a graceful whirl of steel and bloody death.
Tokitaka's Tanegashima (Matchlock) - armed with a beautifully crafted rifle, these heroes put their marksmanship to deadly use.
Seigen's Swordmasters - carrying the fearsome two-handed Nodachi, these heroes strike terror into the hearts of those they charge.
Tadakatsu's Tetsubo Warriors - as strong as Oni, these mighty warriors are masters of the brutal Tetsubo, or war club.
Hanzo's Shadows - an elite ninja unit, unparalleled in the use of stealth and trained to scale castle walls at lightning speed. The ultimate dealers of swift and silent death.

Simultaneously, both Shogun 2 and Fall of the Samurai received sweeping updates that include assorted fixes and AI improvements.

This latest DLC pack is currently available through Steam.