I won't spoiler the details of the matches because I didn't know them either before watching the movie. I knew the overall outcome, but I didn't know the specifics. If you haven't seen it I think it's worth finding out in real time so I avoided Googling about it for a long time :D. The documentary is well made.
The monumental feat to create an AI that can play what is considered one the most complicated board games is definitely impressive.
Lee Sedol's skills are definitely impressive.
What made me think the most and stuck with me is a concept that was repeated more than one time in the film. I'm not quoting here but paraphrasing:
The machine taught me something new about what it means to be a human
To me that's the WOW part of the documentary. Yes we can talk about AI and neural networks, yes we are technicians yadda yadda but we're humans first and well, if we don't screw it up and stop making AIs to show us yet another picture of a dog on Instagram, we have the potential to truly make something mind blowing (well aside using CRISPR but that's another story for another day :D).
AIs that ultimately change or expand our understanding of who we are in the first place.