You asked

Is the yongnuo yn12 35mm f 2 8 4m worth it?

Here is what the site says about that.

From Yongnuo YN12-35mm f/2.8-4M: Yongnuo YN12-35mm f/2.8-4M: A zoom lens by Yongnuo for Micro Four Thirds cameras, 12-35mm f/2.8-4. Specs - Maker: Yongnuo - Focal length: 12-35mm (zoom) - Maximum aperture: f/2.8-4 (it gets darker as you zoom in) - Made for: Micro Four Thirds sensors - Mounts: Micro Four Thirds - Stabilised: no - Autofocus: yes What it frames like - On Micro Four Thirds (Micro Four Thirds): like 24-70mm on full frame; f/2.8-4 gives about ...

From Sensor sizes: Is full frame worth it?: For low light, events, and portraits with very shallow depth of field, yes. For travel, street, wildlife on a budget, and most hobby photography, a good APS-C camera with good lenses is enough, and you'll carry it more. Lenses and light matter more than the last stop of sensor performance.

Quoted from this site's pages.

From these pages