My first impression is that his conjurations and creatures are incredibly powerful, but I haven't even scratched the surface of how to use him properly.
The 4-mana conjurations (Watchtower and Garrison) are incredible because of their cost. They are so cheap that there is no point in trying to destroy them; you can recast them for the cost of a single Block. (and they've probably absorbed more damage than one Block) You need 2 other outposts to maximize the mana income of a Barracks, so there is no reason not to throw down towers early.
The "Soldier" type creatures are all about damage and mana efficiency, but they tend to be fragile for their cost. In contrast, the Iron Golem and Earth Elemental are Slow and immensely sturdy. I am definitely planning to use Golem/Elemental to Guard my fragile slingers and snipers.
The Barracks generates 3 mana per turn and the Goblin Grunt costs 4 mana. This is incredible. Seeing all of those grunts swarm out onto the battlefield made me want to yell "FOR THE HORDE!!".
Becoming good at the Warlord is going to require a lot more skill in positional play. For example, the mere presence of Ludwig Boltstorm (1-1 3 dice triplestrike crossbow) strongly discourages enemies from hanging out in zones adjacent to Ludwig. The presence of an iron golem strongly discourages enemies from venturing into that zone. Caltrops and walls can further "zone out" enemies.
A Warlord creature swarm is very different from a Beastmaster creature swarm in that he is slower to get started and therefore cannot rush as effectively. A BM can make an effective swarm without any spawnpoint at all, or with just a Lair (14 mana), while a WL needs a minimum of Barracks + 2 Towers (20 mana). However, once the Warlord has a lot of creatures out, his extra abilities like Veterancy and Battle Orders make those creatures extremely powerful.
The 3x mana cost for dispels, nullifies and teleports is really painful. A Warlord will frequently have to make do with knives, axes, slings and arrows in situations where a more "educated" Mage would use spells.
