I love it! The cinematography is really nice. And how he captures the action, the pace, sounds, details ... So good! I think there is a lot of potential for a proper Warhammer movie. Maybe NETFLIX will take the risk because 20th Century Fox and Warner Bros surely won't. These big studios are counting money too much i think.
It turns out , that youtube is having a wave of hackers stealing accounts and Astartes is one of them. So forget this link and do not click it. There are a few channels that uploaded a supercut with all 4 parts in one video, so if you really want to see it, maybe search for Astartes supercut, although that will not be the original creators channel either but at least you can watch it without adverts and enjoy this great piece of GCI art.
It's incredible animation and VFX. People not versed in 40K might not notice the little things and how they call back in to rules in the table top and source material. As an example:
When he blows his hand off with the plasma pistol near the end. In the 40K table top game there is a rule called Overcharge for most plasma weapons that allows you to do more damage with the possibility of injuring yourself.
Really great callback to the source material. Also interestingly all the Space Marine chapters flashed at the very end are fan made chapters! The creator of Astartes asked for submissions after last episode and spot lighted some at the end.