I don't regret getting this. Nor the DLC.
If I'd known how much vanilla gear there is I might not've gotten the DLC but it's no big, I really like most of it. I love the suppressor grenade rifle, though I seem to be the only one on Super Earth who does.
For those still looking, there's three enemy factions and a neat little pseudo-cooperative campaign system. Each enemy occupies a third of the space around super earth which is divided up into sectors, one of which is active for each faction at a time. You pick an enemy and then a planet. Each planet has a difficulty rating, from 1 which is pointlessly easy to 12 which I haven't done and can't even imagine, a reward unlock, and a climate which is mostly cosmetic but affects what kind of terrain hazards there are. Stuff like swamps and snow that hinder movement, magma vents that can kill you, and such.
And you and your team do two or three missions on the planet to conquer it, at which point you get the reward and points are added to the region score based on the difficulty and how well you did. When the conquest bar is full the sector is cleared and you move on to the next one. The score required is always hundreds of thousands of points so every player contributes to it.
And when you get all the way to the end then everyone fights on a single homeworld planet working to do the same thing. If you can't fill the bar in a certain time limit then you lose the battle and get pushed back. It's apparently possible to get pushed all the way back to Super Earth and even to lose the war but I can't imagine that actually happening.
Anyway, the enemies. There's bugs which are starship troopers. They tend to have big swarms of easy chaff plus giant tank bugs that can only be killed heavy weaponry or tons of fire at their weak points. Then there's cyborgs who are cyborgs. They use guns with a little melee, and big heavy weapons platforms like tanks and robot walkers. Their armor isn't overall as tough as some of the bugs but some guys have shields which are all but invulnerable if you shoot the shield.
And the illuminates are stupid. T hey're protoss, there aren't that many of them and they're pretty fragile but a lot of them have force fields you have to break first. They mostly fight with spider robots and assassin type units that shoot you at range with lasers it's impossible not to avoid, and crowd control and area denial stuff. I don't like them much.
There's also bosses but i've never fought any of them. The silly teamkilling I honestly haven't seen that much of, it's not like Magicka where you kill each other as much as you kill the bad guys, for sure.