For when you’re doing groups and street, but want it fast.
This focal length is pretty common, maybe second only to 50mm. Easily the most useful prime for most people’s street photography and group photos. Honestly, if you already have a reasonably fast zoom, this doesn’t give you much benefit.
If you don’t know why you need f/1.4, don’t buy this. It’s not a small or light lens by any means. Even if you can articulate why you need it, ask yourself if Sony’s E 35mm f/1.8 OSS version, which costs half as much, is less than half the size and weight, and comes with image stabilization will do the job. Unless you’re just reading specs, it likely will.
If you do need the extra quality and speed, well then, enjoy it.