I loved the warlord. I mainly GM, and only stuck with 4e for the first year or so (then defected to OD&D and it's clones), but Warlord is one of the classes that I got to try first hand with much, much delight.
I have to say I agree with both sides of the argument :
- Warlords are thematically awesome (I love the image of the general rallying his men to keep on fighting);
- Healing someone by screaming at them is odd.
I, though, am curious as to why it wouldn't be somehow folded into fighter. I mean, you could have the fighter as a wild barbarian or angry mercenary, but also the fighter as the grizzled general, inspiring his men. The Marshal/Warlord fighter option could easily be added as a modular add-on, thus only making 4 basic class necessary, and sticking templates on top as necessary.
As such, in a game using class templates, themes, or whatever the word would be, a Fighter could be a Warlord (have some buffing abilities, temp HP, extra movement granting, and so forth), a Ranger (a fighter with survival and sneaking skills), a Barbarian (light armored damage monster) or a duelist (light armored fighter with trickstery combat options)