^As I have said before; if it wasn't a great game then it wouldn't matter if the ending was crap. It is, therefore it does. All the EC really did was fill in the insultingly massive plot holes and glaring omissions. More than anything, it's the best proof to date that the original ending was rushed out the door, not even close the being finished. The basic premise is still very contrived if not outright bonkers.
No matter which way you cut it, introducing the catalyst at the last minute and forcing and A, B or C (and now D) choice is still terrible storytelling. The fact remains that your choices still don't really matter in the end and the whole EMS system just serves to cheapen the experience.
Moving on: assuming they continue to make ME games beyond this point, it's pretty clear that (asuming it'll be set post ME3) they'll almost certainly have to pick one "canon" ending. Am I alone in thinking it'll be the high EMS destroy ending? I can't see either of the others being particularly viable for dramatic storytelling. I mean, what could threaten the Control or Synthesis galaxies with the Reapers still around to protect the peace?
Something else that occurs to me: am I correct in assuming that there's still one more mass relay left untouched by the crucible wave? That is, the one say out in Dark Space and connects directly to the Citadel. What if the Reapers left one of their own behind to guard it? There could still be a reaper out there, presumably now free from control.