well borderlands was probably arguably the first popular "FPS with MMO stuff in it but not an MMO" game...

Usually MMOs mean at the minimum that you have: character progression and mostly persistant universe (stuff exists in some state prior to logout after logout) with lots of players per shard.

F2P usually involves microtransactions which is what they are doing here. I just worry about competitiveness in microtransactional games; devs have to be careful to basically make what people buy that aren't completely out of balance. Usually the tradeoff is instant gratification vs. having to grind for something.