First off, let me make it clear that I think the whole End of the Line project is awesome. The video, the update, the team that made the video and update, all that.
Now let me complain about it.
They characterized nearly everyone so weirdly. Like, the Soldier was good. The Pyro was good. The Medic and Spy were okay to an extent.
But the Heavy? He's smart. Very quiet, but smart. He has a PhD in Russian Literature, we've seen from his interactions with the Scout in the comics that he's observant (recognizing the possibility of Spy being Scout's dad), and in the same interaction he shows a very laconic wit ("Yes. Your father disappears often."). He's also incredibly stoic. In the EotL video, he acts like this dumb labrador seeking approval from the Medic. Then he walks out in front of a train. If he had told Medic to come along and uber him, that would make sense. But why the hell would he just go 'welp, instead of actually evacuating and surviving, lemme just suicide."
Similarly, the Blu Spy. Why did he undisguise when nobody suspected him in the first place? Why didn't they just have the Heavy catch him as he tries to escape without being noticed? It would have made so much more sense that way.
And why does the Blu Engie act so meek around the Soldier? I get that the Soldier is nuts, but in Expiration Date we saw the Engie casually calming the Soldier down.
Anyways, the good: the animation was, overall, fantastic. I noticed that movements that weren't cycling looked far more natural (for example, when a character walks they look stiff and unnatural, but when jumping down steps/climbing ladders/gesturing they looked great). The music. Oh man. The scoring for that video is impeccable.
I remember they also had some interview thing or something where they talked about all the tricks they used to make SFM do what it couldn't do (things like prerendering distant backgrounds and compositing them in, I think there was also something about physics and destructable models, but I don't remember for sure).
All in all, I r8 way-better-than-I-could-possibly-do/10.