The fact that the DLC is over twice the price of the actual game. Just because the practice of expensive DLC is not exclusive to Mass Effect doesn't make it any less sad. 'Funny' thing is that I don't think the DLC prices have went down at all.
They were however far stronger and a far far more threatening enemy.
If my only experience with them had been from the game, I would be wondering just why Cerberus was putting so much effort into them. They were a lesser threat than an Atlas mech.
They are another reason I don't like the Omega DLC. We are told that they are a deadly threat but we never see why.
In the comic they apparently behave a bit like necromorphs or zombies. You get cut or scratched or whatever and you'll turn into one of them too. So if you ever get hit by one, you're a goner. Its like a zombie bite. I thought they were pretty damn weak in the game though. I was popping them off with a pistol and just shaking my head at Nyreen's fear. Like "really? This is what you're so terrified of? Meh."
Though I was maxed level with max gear at the time so... yeah. That might have had something to do with it.