It's the fact the class feels too much like a cleric who decided to specialize in hand to hand combat but kept his focus on healing.
I think the class should have been much more focused on the "WAR" aspect instead of the "PRIEST". As it is the class has a lot of focus on healing (for good warpriests at least) not so much on efficently killing stuff. But as healers priests and oracles (of life) will always outshine the warpriest (and correctly so) while the fighting advantage the warpriest class enjoys is not that evident as to make you want to throw away better healing capabilities and spell casting up to lvl 9.
Long story short: to me the warpriest doesn't feel like he's martial enough. Personally I would have swapped the healing advantages for more powerful fighting advantages, keeping the healing aspect to a minimum.
As a concept I like the warpriest: a divine fighter bringing the wrath of his patron upon the infidels on the battlefield, I just find that the execution missed the opportunity of making it really viable.
I think warpriest is kind of neat, but given the chance(depending on DM), I'd take an Ordained Champion(3.5) in a heartbeat. But ya know, OGL limitations and all.
