Personally, I'm glad they didn't tie it in with Alien as much. It makes for a more unpredictable and therefore more interesting story.
The UFO design may not be as cool as a Giger inspired one, but there is enough Giger in the film as it is so it's not like we are missing anything, and the UFO shape is very much that way on purpose. Plus, it is only two shots of about four seconds each....