The original Xtro was a British sci-fi horror film from the early 80's. It was very silly indeed but pretty original and strange. I guess you could describe it as a minor cult movie. Its director, Harry Davenport, returned almost a decade later to make an American sequel called, perhaps unsurprisingly, Xtro II. This one is only vaguely related to the previous film at best. It's set in an underground military laboratory that is experimenting with travelling to other dimensions. They send a swat team to one such place, it's disastrous and one of the team returns only for an aggressive alien to burst out of her stomach and escape into the facility. The remaining personnel must avoid being torn apart by the monster.
It should be clear from the synopsis that this flick owes a fair bit to Alien. But the truth is that this one isn't even nearly as good as the uneven original Xtro, far less Ridley Scott's master-work. Probably the single biggest problem is the location. Almost all films set in confined military bases are usually tedious and terrible. The limited sets are good for a low budget but very boring. This one is no exception with lots of dark corridors and very little variety. The movie stars Jan-Michael 'Airwolf' Vincent. He's not very good and puts in a thoroughly disinterested performance.
Overall, very forgettable.