I played it a while ago and quite enjoyed it. I'm a sucker for large-scale FPS games. It played surprisingly well considering how ambitious its scale was. It has been plagued with optimization problems, though. And like all F2P games, progress through unlocks is annoyingly slow unless you fork over cash. It's never gets especially unbalanced because of this, though. (That may have changed in the 4 months since I've played it.)
It can be really fun if you get people to cooperate and take on different roles in a squad. If we played together, I'd drive you around in a gunship and you could rain explosive death from above. I'm a good pilot.
You need to find people who actually play really. I've played with a random group or two but when you're on an active server man does it become the best shooter ever.
Having said that there is only so much shooting I can stomach before I get bored but PS2 did keep me around for a month.