Slow pacing can be considered an essential part of the story. It certainly aids with building tension and fits in with a space mining crew that would be sat around with nothing to do for long periods of time.

Maybe part of the problem is that due to its success, a lot of the designs and themes have been copied elsewhere, so it's less captivating. Back in the day, there was nothing like those Giger sets, so people were quite happy to see a slow descent into an alien spaceship.