The lights are on
ME2 was the best ME game. If you start with ME1 you will be compelled to finish all three simply because the of the storyline. I did not get caught up in the ending controversy - to me a good story is everything that comes before the ending - more of a "enjoy the ride" way of looking at it.
One issue I had with ME3 was not being able to port my Shepard from ME1/ME2 - I got connected to that guy and in ME3, I could not get the look right. It seems minor but it bothered me the whole game.
One day, I will start a replay of all three. When I play a game with "choices" I make my choices and play straight through rather than seeking certain results - I am thinking of playing as a female Shepard and it will be interesting to see how my choices change.
I played the XCOM demo, I did not get hooked.