The first thing I notice about the Warpriest is that it’s not really one build; it’s a bunch of builds, one for each divine domain. The domain makes a huge difference to a warpriest: about 13 powers, including the cleric’s at-will powers, and several class features are determined by the domain.
Only two domains, Storm and Sun, are listed in Heroes of the Fallen Lands. This marks out plenty of room for further expansion, which is a good sign for 4e.
As a player, I want access to all the domains now. I want the complete warpriest! In the economic model of D&D, though, “complete” means “dead”. 4e relies on the developers continuing to dole out new material. When they can’t think of any more stuff to dole out, there’s nothing left to do but make a new edition!
For reference, here are the domains listed in 4e’s “Divine Power”:
arcana, change, civilization, creation, darkness, death, destruction, earth, fate, freedom, hope, justice, knowledge, life, love, luck, madness, moon, poison, protection, sea, skill, storm, strength, strife, sun, torment, tyranny, trickery, undeath, vengeance, war, wilderness, winter
It will take a while to flesh out each of these with class features and powers. And even when the Warpriest build has been completed: WOTC can introduce a new build and start again! May I humbly suggest PEACE PRIEST