Could pretty much quote what Will said.
I played the fuck out of the first on xbox, then played the second on it too. Then when I switched to PS3 I played the second and third on that.
The first was my favorite. I loved everything from how in depth the the info on each race was, the story line, the weapons and how they could be modified, the background music, the locations... it was all awesome.
I just finished the third. I though it was still a great game but I agree with most of the hate on how all your decisions over the previous 2 games made almost no difference.