Those Giant made World Sports and World Tourers are good bikes for low end bikes. I had one that I picked up for a flip, rode it around and was impressed at how nice it rode, even with the steel rims. The paint job on these bikes were pretty good too. In your example above, it has a gold head tube, not that painting it gold makes it good, but it is an extra expense on a low end bike. The one that I had was black with gold lug lining. Brazing was excellent. Giant was trying to impress Schwinn.
1020 steel, fully lugged and with good Schwinn designed geometry. Not a bad deal.
When I worked in a Schwinn dealership in the early '80's we sold plenty of them. We would have sold more if I was more on-board. I wasn't (at the time) because I saw them as a lesser Schwinn. I was wrong. This was the very beginning of bikes coming from Taiwan and I was skeptical.
The owner of our bike shop also contracted with a Taiwanese bike maker to make private label bikes. The prices that we were able to sell them for was comparable to Huffy, Murrays and Free Spirits. After an initial correction for Bass Boat Metal Flake the bikes looked good. We sold a bunch of these bikes too including to other dealers on Long Island.