This gives some long overdue love to the traffic in space. There now should generally (depending on the planets in the system) be more traffic in space and they should behave more like traffic (e.g. descent/ascent to/from planets, enter/exit stations and gates, etc.). You might also see more traffic flying between certain planets now.
If you don't like this (although I suggest you give it chance because it varies greatly between systems) you can change it via the System traffic density setting.
Other than that, just a lot of bug fixes again.