Saw this last night. Was quite impressed.
Not without its' flaws: unintentially amusing at times, characters inexplicably stupid from time to time, themes could have been developed further.
However, the acting is strong; while it starts off slow, it isn't boring, and while the final third is a little predictable (if you go to an Alien movie expecting unpredictability, you're doing this wrong), it was well-enough signposted without being too obvious and extremely well-paced overall. SFX are good enough, though not mind-blowing; acting is strong, Michael Fassbender in particular is fantastic. Storyline within the wider franchise is compelling.
4*s out of 5 for me. Moderators, you should probably not see it as there's a fair amount of profanity in the film. Otherwise, if you're a fan of the franchise, go see it.