In defense of the Envoy, I think they can simply do some things better than any other class can, namely debuffing. Consider a level 1 Envoy with Dispiriting Taunt. Every round, this character can ensure an enemy has a -2 to attack rolls, and likely will instead be shaken. I don't think any other class can do that. Even if they save, they're still off-target. This can be done at will as a standard action. I think that's a pretty solid debuff at level 1. At 4th level, this can become a move action. At 6th level, you could take Draw Fire to give every enemy a -4 to attacks except against you. That's awesome! Draw Fire, dive behind cover, fall prone and the entire enemy team just got a major debuff on ranged attacks, which I assume are going to be common.
Additionally, it's one of the few classes that has the ability to heal other characters' stamina points. The Mystic is, of course, the primary healer, but Inspiring Boost looks like one of the few effective heals I've seen that can essentially be used once per ally per battle.
Also, looks like one of three classes with grenade proficiency, which is a nice bonus.
