Since the way the wording works this card can reach insane ATK and Command bonusses in an Aun'Shi deck. However having said that he only does this for Aun'Shi. 

4/5 (For Aun'Shi. With only not being a 5/5 because he only has 2 HP and does not always have the bonusses)

Note: For each Ethereal unit you'll recieve the bonus. Keep him around Aun'Shi and his signature squad and you have a Warlord killer right here.

Except for the ocassional combo with Kauyon Strike to hit for over 9000, I don't see this card being better than Bork'an Recruits.

I'll give them a go once the pack arrives, and they will hopefully prove me wrong, but I have a bad first impression.

Except for the ocassional combo with Kauyon Strike to hit for over 9000, I don't see this card being better than Bork'an Recruits.

also a combo with Prelate or Ethereal wisdom.

also a combo with Prelate or Ethereal wisdom.

and Envoy! 

They are an alpha striker.  I'm not sure I've ever swung with the Grenadiers when it wasn't at the enemy warlord.  And if he gets to swing, there's a good chance it's for 7 or more with armorbane (between Ethereal Wisdom, Honor Blade, an ambushed Prelate, Envoys, and Aun'shi).  Sure, he can get routed or exhausted with a number of effects, but a) he's 3 cost, not 5 or 6, so it hurts less to have him blunted, b ) try to set up your alpha strikes for when you have initiative, or else use Ethereal Wisdom on the Grenadier and bring the entire combo in from other planets with Kauyon Strike and Orbital City - those things don't guarantee he can attack, but there's a better chance, and c) if it was TOO reliable to get 7 armorbane on the enemy warlord, the game would be no fun.

The problem with the Grenadiers is that they're too fragile to survive a round of combat, and suffer from all the usual spot removal. You need a lot of setup to make them work, they're mostly telegraphed and your opponent has a number of options to dispatch them.

We can compare them to what I believe is a core card in Aun'shi, the Bork'an recruits.

All I've said above is true for them, but Bork'an cost 1 less resource and don't need an ethereal to gain a command icon, which is critical, since it means they can act as a dangerous-to-snipe capper.

They cannot reach 7 attack, but if you manage to hit for 5 armorbane (Prelate or Wisdom Bonus) it's usually enough to kill a Warlord and sometimes even to bloody them - Aun'shi himself attacks for 2, so there's a very good chance the opposing WL suffered at least a couple points of damage before.

Looking at other options, for 1 more resource I'd very much like to have Warrior Cadre. Ranged is huge for Aun'shi, and if you happen to have the initiative as well you can almost guarantee a bloodying.

I'm not saying the Grendiers are outright bad, I just think  that, considering them as they are right now, there are better options for Aun'shi - which makes them a dead card IMO, seeing as deckspace in Aun'shi is already very tight (it's pretty much a given you need to run 3x Kauyon 3x Orbital 3x Prelate) and  they don't do anything to mitigate the weaknesses he suffers from: opposing Ranged, army removal and serious hunt decks (not to mention the constant need for cards, which is arguably the biggest).

On a sidenote, if they had 3 or 4 HP I would seriously consider them, while with Ambush they would be OP.

I, of course, also run Bork'an Recruits - Recruits and Grenadiers serve basically the same purpose, but I find it nice to have 6 copies.  The enemy warlord frequently can't avoid all copies of both of them.  Bork'ans cost 1 less and are equally as fragile as the Grenadiers, but don't have the huge offensive upside.

Yes, it takes a lot of set up to make the Grenadiers work at their best, but it's all set up that you're already playing.  All of the combo cards combo well together and don't require a long chain to work well.  But when you do have the long chain, they work even better.  One set of 3 cards - Grenadier/Ethereal Wisdom/Kau'yon Strike is already a hit for 7 armorbane from anywhere, untelegraphed, that is only counterable in the action window before you strike.  And if the Grenadiers were Terrored and you have a Ksi'm'yen Orbital City, then they come right back in and swing anyway.

Just having the Grenadiers parked at a planet with an Ethereal Envoy is a 1/4/2 that scares away enemy warlords, which isn't bad.

The Bork'an Recruits are a decent fill-in, but in my plays, they haven't been an MVP in Aun'shi like the Grenadiers have.

The Grenadiers are not ethereal, so no use for Ksi'm'yen

They are if you play Ethereal Wisdom on them, which is what estyles was getting at.