Clean and beautifully filmed.
Artistic camera work.
Atmospheric and appropriate lighting.
Stellar and creative practical effects.
Mediocre story and a lull for drama's sake that quickly picks back up.
Engaging performances from the leads, and entertaining drama from every extra.
I did not go into Xtro looking for a stellar film, for good technical merit, for any sort of decent acting, and I still got a legitimately entertaining film.
To anyone who loves good sci-fi horror or good special effects- go watch the shit out of Xtro.