In this short text I will try to give my impressions and ideas concerning Brotherhood units. Keep in mind that those are just my opinions (backed with only little experience) and they may change in the future. Most of the information given here is quite obvious but I hope that even more experienced players will find something interesting. I encourage you to leave comments and give your own ideas about presented units or units from other armies as well.

The next unit on the BROTHERHOOD list is INQUISITOR. As I said before talking about SACRED WARRIORS both units are IMO the icons of BROTHERHOOD army and my favorite units (in terms of appearance) so far.

INQUISITORS have very low cost only 35 points per model, at the moment there are only few units that we could compare them to in terms of role in the army, that are: DEMON HUNTERS, RAZIDE, ATTILA. There are some points differences but the function of those units is similar, to deal damage on distance either to many single wound targets or to deal with multi-wounds enemies. Then what do you get for that points:
- RS (15) ( may be increased +2) makes them decent long range fighters,
- at first sight their weapon JUSTIFIER doesn't look like anything special but if you read the special abilities you realize that it's a beast. With TTB 1 it gets +2 ST so with aim you get ST (19) CRITICAL FORCE (3), and it gets even more deadly at the range of 6” or less when the basic ST is (18) and can easily be increased to ST (20),
- the most distinctive feature of INQUISITORS is WP (18) that makes them the most effective ART using unit in the army, and as effective as most unique characters,

The unit must take one ART power and may chose to take the second for 15 points each (with some exceptions).Because one ART power may be taken for free it means that some of the more expensive ARTS that we would never conciser taking became valid options. Depends on the type of warlord chosen the ART powers may differ being more, less or completely useless for a particular unit. Here are some options I think are more competitive than others:

RANGE WARLORD, CARDINAL'S SACRED DOMINION – probably the first pick if you go for shooting heavy army, with +2 RS and AIM they get RS (19) on the first shot and RS (17) for any other,
RANGE WARLORD, THE PERSISTACNE OF TIME – this is one of the ARTS that are too expensive to take normally, but since INQUISITORS may avoid paying 30 points for it you may find it useful giving every model one extra action that may by used to move or hide,
ANY WARLORD, ASCENT OF RUBYT LIGHT – under different warlords has different additional effects, but it is efficient all the time. Being able to include RANGE 32”, AVV 6 ROF 1 (EDIT: it has been confirmed that ART powers aren't weapons and as such cannot have ROF and ROA increased by TTB) and CRIT DAMAGE(2) its just devastating against vehicles, at the same time ST 15 and CRIT FORCE (2) may seriously hurt multi-wound models (even more because it bypasses IMPENETRABLE ARMOR)
PSYCHIC WARLORD, CLEANSING BOLT OF THUNDERUS LIGHT – if you think that WP (18) is not enough to hit the target with RUBY LIGHT, why don't you give the unit re-roll, just to be sure that it will find the target,
ANY WARLORD, ENCOURAGED CORPOREAL FORTITUDE – I don't think it's better that CLEANSING BOLT but still WP (20) is not bad,
ANY WARLORD, FORTITUDE OF THE PENITETNT – if you want to make your INQUISITORS more resilient this ART will increase their IMPENETRABLE ARMOUR to (12),

ARMY COMPOSITION

In my opinion there are two major builds that we can chose for INQUISITORS. One of them is to use them against infantry. They may not have as many shoots as other units with this function but with very high RS they make up for smaller number of attacks with better “to hit” chance. This option is especially effective when we have RANGE WARLORD which allows taking the right SACRED DOMINION and +2 RS. With this build I would take full unit of 4 models for 140 or 155 points if you want to take the second ART power. The thing with this option is that BROTHERHOOD has enough anty-infantry options with other units anyway.

IMO the role that suits them much better is anty-vehicle unit when you give them RUBY LIGHT. In this situation RANGE WARLORD becomes the least effective option because RS statistic doesn’t matter and the ART itself has only 20% of becoming CRITICAL DAMAGE (2). CC or PS WARLORDS are much better in this situation since they give CRITICAL DAMAGE (2) by default. RUBY LIGHT also has longer R than any typical anty-vehicle weapon so it is easier to stay on distance. The only downside of this ART is that you can't AIM with PSYCHIC POWERS so you won't be able to chose the target's location.

Being able to be fielded not only as a SUPPORT choice but also as a leader of any TROOP choice INQUISITORS may easily became a pain in the neck.

Inquisitors as leaders of troops squad bust still pay points for the first art power. Is it correct? They have one free art power only if they are in a squad of inquisitors. Please give me confirm, thanks.

I believe so, the free ART power applies only to the unit of INQUISITORS not to the unit of TROOPS with upgraded leader.

Seem Prodos have included two new inquisitor models in the brotherhood starter box, these models will be used as squad commanders.

I like this idea very much, I was planning to but an additional starter to get cards and extra troopers and judicator, now I will have more Inquisitors rather that useless Dominic

Has there been an offical response on this? as having to buy the art power means the INQ upgrade is really expensive.
Base troop cost + 30 points INQ + 15 Art.

Yep, it's a squad upgrade for an inquisitor squad and not an upgrade for a model. You pay for Art if they're a SC. However, you also get their LD for your squad.

I think the 7 points you pay extra (12 for the Trooper + 30 for the Qinquisitor upgrade VS 35 for the Inquisitor in an Inquisitor Squad) are fine: You get LD 18 and WP 18 for your squad. The 15 points for the Art would have been payed anyway and with the Inquisitor as a squad commander you have a 2 wound squad commander an the Art powers are way more reliable.