The dialog tree was pathetically simple, and the choices clearly divided between good and evil without the slightest hint of grey or morally conflicting choice. The story was good if you ignore the fact that it progressed identically whether you were good or evil. The characters and dialog were cheesey and droll, and the "romance" was slightly worse than what you could expect out of a bad B Movie. Sidequests and planets were as you said horribly repetitve, and technical issues were awful on the 360 version (not present in the PC version which I played).

Overall, aside from the combat system, Mass Effect was a fairly large step brack from what Bioware did even in KOTOR.

I didn't find the dialogue pathetically simple at all.  I found a lot of ambiguity.  I saw the same thing in the way the story progressed.  Have you played the game a second or third time through?  There are substantially different endings, pieces of backstory, and many seperate side missions you will never have seen if you don't play as both good, bad, somewhere in between, soldier, vanguard etc...

But once again, I agree that 80% of sidequests were repetitive and the framerate (and to a lesser extent pop-in) on the Xbox 360 version was ridiculous.

oh well, I will play it on my PC

Play Neverwinter Nights 2: Mask of the Betrayer if you actually want to see a game with brilliant dialogue and story. Easily the Best of this generation so far.