As has been said, you end up replaying a lot of it. However, there are different encounters each time (as it's all semi-randomly generated) so you're not exactly replaying the same content over and over.
This ^, I played for 2 hours yesterday, died about I dunno, 7 times? and the 'Jump map' was different every time and I even had a nebula with 5 points of interest in the first sector