After a couple of plays I've drawn some tentative impressions of the new units contained in the Dwarven Battalion expansion pack for Battlelore.
The most unusual unit is definitely the Iron Dwarves Bagpipers. I'll confess that they didn't p;ay a big role in either of the fights I've seen them in so far, but that's largely because I deliberately targeted them for early destruction because I feared their power. While only able to inflict retreats, they roll more dice than any other ranged unit (up to four dice for the Red bagpipers) and are particularly dangerous for Goblins who have the fear the effects of a Goblin Run. I would definitely consider adding them to an army as a specialist.
The Iron Dwarves Spear Bearers are another fearsome unit. Spear units shine when the battle back and as dwarves these guys will always get to battle back. Their battle back strength deters engagement, especially by green or blue units, so they tend to divert an enemy attack into other sectors. Another very useful unit.
The Iron Dwarves Axe Swingers, on the other hand, are fairly ordinary. It's true that they are slightly better than the blue Dwarven swordsmen, but their special ability bonus won't come up often enough to make a big difference in most games. I suspect they'll only be selected as specialists when there aren't other choices as they don't really bring anything unusual to the table.