I really liked that 4th episode. Just as a longtime fanboy, this was riveting. At the end I was close to the edge of my seat and really wanted to know what's up with Rafael.
It is not great TV though, if I am being entirely honest. Like Brother Indefragable said, the marines act a bit amateurish. Their professionalism (hypnodcotrination and all that) is sacrificed for dramatic effect. No perimeter, casual glances into tubes and pipes, firing way to late into the oncoming horde and the Deathwatch vet removing his helmet but not redonning it when the enemy shows up. It's a bit inconsistent and a stark contrast to the deadliness of astartes shown in, well, Astartes. There we have way less drama, but see the ruthless efficiency of the marines.
Here we get the personalization, the drama, basically more story-telling (which I really enjoy), but the fact, that the marines are marines gets lost. If you combined the visual craft and display of the marines of the Astartes series with the storytelling of Angels of Death, you'd get something incredibly beautiful. And they really need to fix the sound design. As someone said before, the Heavy Bolter has a way less chunky, weighty sound than the standard bolters. And boy, that chainsword sounded way to quiet and dampened. The voice acting on the other hand I like a lot. I always thought, that Black Library's narrators and voice actors were great fits for astartes, with all that authority dripping from their voices. And that GSC magos, that voice sounded almost childlike to me, which made it all the more creepy. Loved it!
But seriously: On it's own Angels of Death is fine as it is. Could be more, there's still room for improvement, but it's far better than I expected it to be. And even if the marines are not all what they are supposed to be, seeing 40k in this form of cinematic portrayal is just really cool. Just because of this show alone I'm quite happy to have subscribed. And then there's the batreps and the masterclasses on top of that. Only loremasters needs some improvement, as much as I like Wade.