Heck yeah, I've been following this game for Ages. There's a huge thread in the MMO forum on this with a lot of info and gameplay footage (but you can just youtube a ton of that up). To give people a quick idea of the game...
Its a self-titled "spy-fi" genre, set in the future. There's an orwellian commonwealth force trying to control the world and you're an agent that has escaped. The gameplay itself is very TF2 influenced, but added in there's co-op pve as well. You can gather gear for different loadouts for each class (recon, medic, assault, robotics).
You don't have to subscribe, you can keep playing from just the single purchase and do the co-op and multiplayer fun, but you can also choose to subscribe and take part in the persistant world campaign to control everything. Campaigns reset every few months (last I heard), and give you resources to build better equipment. You have some control over automated defences and stuff so even when you don't have #'s it 'may' be protected enough. Oh and being a subscriber also gives you continuing content unavailable to non-subscribers (new co-op pve stuff).