From the descriptions on here I was well-prepared for a very hard form of sf. So I was pleasantly surprised to find this book to contain many lighter-spirited moments as well. Sure, the titular story is very technical (and a bit dry), but for me it was made interesting through the amazing world worldbuilding throughout, with the later stories also back-referring to other stories. Some interesting technology and the depiction of alien races (and the foreigner's look on Earth in "Flatlander"), too.
To be honest, I liked the less "physical" stories (the ones after "Neutron Star" and "At the Core") better than what it probably Niven's more popular work. Niven has some interesting takes on familiar ideas like decisions under uncertainty (in "Flatlander"), mental health and responsibility (in "The Ethics of Madness") and evolution (in "The Handicapped"). Actually, espeically "The Handicapped", but also the general feeling, made me think of Lem's earlier works (which is a good thing).

Unfortunately, my German version is missing half of the stories. I should look out for "A Relic of the Empire", "The Soft Weapon", and "Grendel". And I should certainly get my hands on Ringworld!