If you're sick of all the modern battlefield of honor games trying to be the same thing, this is probably the one for you.
It's pretty rare that I get into a competitive FPS these days, let alone one that's actually heavily populated such as this. I honestly never expected this to be so popular and I think a heavy part in that is due to the awesome F2P model they're using for the game. I've got 4 classes almost maxed now and haven't spent a single cent of my tribes gold that I got from pre-ordering.
If you enjoy the game and want to get things unlocked but don't want to spend much I'd recommend just buying something from the store to get VIP status (which nets you 50% more XP in-game which is used to purchase upgrades).
Be weary though, it's not the sort of game you can jump into as a new player and instantly start killing players left right and center. There is a large difference between the class playstyles and they all take their own fair share of practice to master. You can get good at one and then become a complete noob again moving to another class.
But that just gives the game a tonne more replay value.