The new GW starter set for Tau is an amazing value and I would encourage anyone who has the spare cash to pick it up. More on that HERE.
Aside from the amazing deal, it comes with a little bit of bait for those that can't stand to be left out of anything. It is an 'exclusive' formation: Ethereal Honour Guard.
Now I know what you are thinking, "BS4 Fire Warriors! Honour Guard are back!" but you would be wrong. Sorry. Not that BS4 Fire Warriors are that cool anymore. We have so many ways of boosting accuracy it is almost unfair. So let's look at what this formation actually does.
Ethereal Honour Guard
Required: 1 Ethereal on hover drone, 1 Fire Warrior Strike Team, and 1 unit of XV8 Crisis Suits.
Bonuses: at the start of your movement phase you can "reform" a unit that starts within 12" of the Ethereal. Only one model in the unit has to remain stationary, the rest are redeployed within 3" of that model.
Since the starter box has all the components for the formation, this means you can play with the starter box on its own with nothing else. Pretty sweet. Unless you wanted Breachers, then you are out in the cold.
The bonus is nothing super amazing, but in a small points game (like maybe starter box vs. starter box) it could be huge. If you keep your models spread out, you could get some massive movement out of the bonus, especially considering that you can still move and run like normal after the redeployment.
Naturally, this turns out to be a better defensive bonus than an offensive one, but it could help you get all your models within Rapid Fire range if the enemy is flanking your spread out mob.
Imagine this: 12 strikers spread out in a huge line, the Ethereal attached on one side to act as bait. The whole line is 36" long. Your opponent doesn't take the bait and deploys his assaulty units in the center to minimize your escape. Let's say he gets within 12" of your center after he is done moving.
You redeploy everything to one side. Suddenly you are more like 18" away from him even though he was ideally placed. Then you move 6". Maybe you even Run and use the Ethereal power to snap shoot at stuff.
If your opponent doesn't know about your formation, and deploys opposite the Ethereal, he will go from 12" to 30" in an instant. Even if he inflicts casualties on the center, you can still redeploy before being forced to move back into unit coherency.
Note: It isn't clear what happens if you can't fit everyone within 3" of the stationary model. Theoretically, you could run a full crisis team with drones that would definitely be too big, especially with the larger XV8 bases.