Yes! Still scary. The realism of it is alarming to this day.
To draw an analogy from fiction, what would happen if one sent Giger's Alien in all its glory, razor tail and all, to compete in an entry-level boxing match? The Alien has no rules, has acid for blood, tongue-crushes the skull of the referee, and so on.
Yeah, they got vented into space et cetera, but I'd say in the first 2 movies humans actually failed to kill the xenomorphs (eggs on LV-426 and aboard Sulaco). At the end of the third movie the newly born xenomorph queen clearly dies. However, in the fourth movie the xenomorphs are again brought back through cloning.
Also, in "Prometheus" and "Alien: Covenant" it becomes apparent that the original crashed ship on LV-426 in "Alien" was not one of a kind, there were tons of ships carrying the gooey secret sauce of xenomorphs.
Also, at the end of the second movie the queen xenomorph was simply vented into space, but whether it died or not was not very clear. I mean, the xenomorphs seemed to be quite resilient and not too picky about things like atmosphere and cold temperatures.
So, not really alien at all.