If I am to remember correctly this movie is not half bad until the alien 'hatches' then it goes so far downhill it'll make you feel like your on a rollercoaster.
One particular point sits in my memory, the 'alien' has just escaped and the scientists need to go to the surface for some reason. They make a big deal about how hostile the surface is and how no one could survive on it, but damn it he has to go out and fight the alien. Then they override the computer and open a hatch to ... the south western US! Now we get to see some dude in a suit walk around for like 5 minutes while they blow smoke infront of the camera to make you feel like your in an alien landscape. I believe you can even spot tire tracks on the ground and a rv in the back ground. Then we get a close up of the actor's face looking surprised, a close up of some purple weird dragon head going 'ROAAR' and then the scene of the dude running back to the hatch.
My friends in I had to break down and start laughing, it was one of the most inexplicatble sequences in film since the burlesque scene in Glenn or Glenda.