Just finished the final story mission, I really have no idea who the last bad guy was, who the evil factions are besides "bug head guys, devil guys, and robots" (or why they are fighting each other and us), or pretty much anything. Just a terrible, terrible story/plot/immersion/advancement/everything single player. I think Battlefield 4 had a more coherent single player campaign.
Still the game is fun, I am enjoying PVP and getting slowly better at it. My D2/MMO days are long behind me, not gonna sit and grind 8 hours a day for +gooder stats, especially with the goofy dungeons that all are the same mechanic boss-fight wise. But if I can slowly eke out small gear upgrades with a few PVP games a week I'm happy.
Oh if you go to Earth and hunt down those level ?? we saw in beta, turns out to be level 20 mobs. They have an entire small area down there with an Ogre, two Wizards, and some trash. Opens up a cliff side that connects to Fallen Shore. Didn't find anything around there (chests nor dead ghosts) but it was fun exploring around a weird little level 20 minizone on a level 1-8 Planet.