RE: Impressions of Alien: Romulus

Watched this recently and I felt the movie had a slow start, but they made up for it with a believable storyline, although this is a well known pattern (Human finds alien, alien tries to kill human).
I felt the aliens looked like something I would believe, and the action was quite ok, but then there was no wow factor about the movie. And just like you mentioned, I'd almost forgotten about it until I came across it now, so it's quite easily forgettable.