I only have ME1, but I can't really play it because my computer is utter crap and ME1 chugs even at the lowest settings. I'm personally waiting for either ME3, or a "collection" that has all three games together, if Bioware ever makes it. I'd like to at least, you know, PLAY* the series before it gets past its prime.
*I got a ways into the first planet, but then I had to change computers and I lost my save file...So I gotta start over. Bawwww.
Speaking of playing, are there any things in both games I can miss after a certain point in time, aside from permadeaths of party members, like sidequests or special items/weapons that could be considered game breakers?