If any one group is skeptical, whether it be the shooter fans or the traditional MMO players, I'd say the MMO crowd may be skeptical more so than the shooter base. I've played both types, and I can say I've been waiting for a shooter to come along and successfully merge both genre. I think Planetside is the closest game I can think of, but it failed in many respects.
A skill based game with teamplay mechanics, multiple classes, and the ability to customize your character, using multiple talent trees and the combination of equipment slots to make a truly unique avatar? That sounds pretty good to me. If GA's gameplay alone is as exciting as what the Alpha/Beta testers, the spectators at the gaming conventions, claim it to be, imagine the MMO elements and territory control factored in.
For those of you who have just stumbled upon Global Agenda, I highly recommend you find out as much as you can about it. Goto the GA website and read the features, read all the articles and watch the videos.
So, to answer Susan's post, I'd say the answer is a definite YES.