ME2 didn't advance the story anywhere, and only introduced a hole in it.
it all revolved around how Repears take the form of the Organic life they were created from. with the grand finale of battling a half-done human Repear.
so how come there is only one form of Repears?
for the fussy among you, the ME3 codex states there are 3 forms of Repears, but they are just different size, to have something similar to a Cruiser, Destroyer and Frigate.
but it also states there were many many cycles. All of the life forms up until now had the same shape?
the original ME3 ending left a lot of questions unanswered. like were that catalyst/child came from in the first place.
the extended cut is what it should of been.