Global Agenda has a lot of things going against it. Bland environments, limited choices, loose gunplay, and the lack of meaningful loot will make you think twice about leveling your character to 50. The MMO part is questionable at best, and there are a number of flaws that need to be corrected before you should consider taking the plunge.
Perhaps the most damning flaw is that titles like Guild Wars, Team Fortress 2, Shadowrun, and even Borderlands already do most of what Global Agenda does and they do it better. They also do so without relying on any added monthly cost, even if it is entirely optional. Let the buyer beware.