It took me an evening to finish the add-on, which was enjoyable in the end, despite much easier than the main game (but of course that's not the case). The merge between the main story and this add-on was very nicely executed and interesting. Even the various built-in modules and the navigation system is a bonus.
Generally, well executed add-ons, add to the atmosphere of the concept in general, therefore I'm hoping for add-ons for the second and/or third game as well.
Keep up the good work Stefan.