The motherfuckin Thorian. The fight up to the Thorian? Great. The Geth are moderately intelligent, and the level is a joy to play - tense without being obnoxious. The Thorian itself? I had to save scum a bit to get through it. Limited healing, an enemy that is impossible to take on with my build's strengths, and the SECOND dumb mind control plot in the game make the Thorian my least favorite part of ME1 so far. I think I'm pretty close to the end at this point, just some side quest cleanup and one or two more main line quests.
Some of the DLC counts as a main line quest, which seems to have advanced companion dialog a little faster than was intended. Whoops.
Here's the video.
Watch live video from Confessional on www.twitch.tv