I'm thinking about buying it. I like MMOFPS like Planetside 2 - does it have similar climate?
No, not at all. By climate, I assume you mean massive scale battles with like 500 vs 500 players with vehicles and shooty lasers everywhere. No, Defiance does have "massive" battles but it's all coop (unless you play PvP but that's much smaller scale, like 8v8) focused to take out the ArkFalls and bug bugs. There are also vehicles, but except for your OWN vehicle that you get to move around faster, there are no tanks or flying vehicles etc. Not that I've seen so far yet (Ego lvl 78 btw, whatever that means lol)
And yeah, I'm liking the game so far. It's obviously not a finished product sadly, but the combat is fun and feels pretty damn good to me. I like the voice work (for most of the characters that is) and the story while kinda cliche seems decent enough. I am looking forward to how they connect the game and tv show, though I'm gonna guess it's just a periphery type thing.