4/5 stars. The rules are good.
We interrupt the regular chain of events here to review the Effrit Stealth Squad -- for no other reason than I have been waiting for this one to come out since the Exemplary Battles in the Age of Darkness series commenced. That, and I always liked Omegon in the Black Library books being in command of this secretive cadre.
The Alpha Legion is no stranger to infiltrating deadly squads in to position, and the Effrit are similarly tasked with missions that might be suicidal for others.
Two wounds, and BS=5 makes for mixed strengths. They have good attacks in close combat, but need better AP to be fully effective in this role, while their 3+ armour save is distinctly normal.
They do come with a variety of upgrades such as infiltrate and scouts (nice), along with a Hydra's Wail disruption array to cause Ld penalties on enemies in closer range, shroud bombs to keep them alive longer, and some banestrike shotguns which is very interesting to find here! Shred, breaching, and concussive makes for a very strong close range threat.
More durable than headhunters, this unit suffers from a bit of an identity crisis. I feel that they need to be upgraded in one of two ways: either with the nemesis bolters for longer range work, or with the power daggers to ensure they can hold their own in the inevitable melee that will following their shooting phase. Final problem is that they are elites and thus take up a crammed slot on the force chart.
5 Effrit, All with Nemesis Bolters (195 points).
Exploiting the BS=5 from long range, the idea here is to set up and ping the enemy until it dies. I think this set up is actually a bit of a waste. You might be tempted to instead toy with the idea of one or two nemesis bolters instead but there's no easy way around the heavy 1 implication of these weapons.
5 Effrit, Power Daggers, Melta Bombs, Principal with Power Weapon (200 points).
A much better proposition! Use those banestrike shot guns to whittle things down (don't forget the Wail) and charge in to mop up the rest. The power daggers shine here. The power weapon is subject to taste - the sword is nice enough, an axe gives that AP2 that might be needed (but is unwieldy) whilst a Maul gives improved S, and the lance could be great in the right scenario too. I'm torn on this aspect. Add in 5 more members for 105 points and you have an infiltrating force to be reckoned with here.