I finished #4 last night and I completely agree. I think Ferreyra's artwork is the best of the lot so far and possibly the best since Den Beauvis. His humans, his Elden, his Xenos, his Engineer, his environments. I had absolutely no complaints with the visual side of the story, at all. I really hope Dark Horse take him for future projects.
That said, it didn't feel like a conclusion at all, as you said. It's quite clearly Part 1 in a 3 part story. I don't think the others will end on such an anti-climatic note as they both have their own individual stories to wrap up - Elden, Francis & Predators in AvP, and Galgo, Ahab, the Engineer and LV-233 (I think that's the right planet, I don't have the comics with me atm). I think Aliens has the potential not to end adequently but we'll see.
Spoiler
#4 did have some awesome moments in. The Engineer vs the Aliens. And then towards the humans. I was like "Daaaammmmnnn". I loved seeing Elden lose his shit like that.
It was a good comic. Just a terrible conclusion. Once everything is finished and we've gotten Omega, I'd be interested to see how it all reads then.