My first 35mm camera was a Yashica rangefinder with a fixed 45mm lens. I took many of the best pictures I have ever made using that camera. The diagonal of the image frame (film or sensor) is about 43mm, so this really is a "normal" lens by that guideline. This lens sounds good, but since I don't ever find the need to shoot with my 50mm f/1.4 lens since I've gone to full frame, I doubt that I'd find the 45mm any more useful.
There was an advantage back in the '60s of using the same focal length all the time, especially one with such a normal looking view: I could previsualize my composition very easily without picking up the camera. I had the picture in mind before I looked through the viewfinder. It was probably good for my education as a photographer.