You are correct about the CB350-F being a low-powered bike in comparison to similar sized twins that were also available in their day. The appeal of the CB350-F is that it has four cylinders and pipes, making it much smoother than the twins. Also, the sound from those four pipes is much more exciting. The design of this SOHC-4 mimics its larger siblings - the 750 and 500/550, and undoubtedly the 750 was the most sought-after and revolutionary design of Honda when it was first introduced. So, this 350 model shared the appeal. The 350 is much lighter than the 750 and can be tossed around the corners more rigorously. That can make its ride exciting and very enjoyable when you hear the four exhausts snarling at the same time. The twins cost less and went faster, but these other points make the four just that much more attractive to many.