I saw it today. It's good, but not great. But to be fair, I don't expect an alien movie to ever be great again. It's very well made. Pays homage to the history and fits perfectly within the first 2 movies. The mood is good, the flow is good, its a solid sequel. As an avid fan, I am very happy with it.
Nit picking stuff, overall I wasn't happy with the climax of the movie. Nothing wrong, but personal preferences make me not like the third act so to speak.
I also didn't like the cast all being "teenagers". I mean, they're in their 20s but they look ultra young and definitely don't look like working stiffs from the mines. The opposite vibe of the nostromo crew.
Would any of that stop me from recommending it? Nope.
Nope, in fact I'm glad I didn't see it in IMAX. To me, IMAX is only for larger than life movies. Nothing in Alien would really benefit from it.