The 25mm is soft around the edges with a visible gradient from its widest f/1.4 to about f/2.5, after which the corners gain uniform sharpness and the gradient clears up. To be honest, the gradient isn't a problem for us as we like the aesthetic, but it may bother some photographers. Check out our sample photographers to see if you can spot it.
The 25mm is a dream lens for portrait and low-light shooting, but like all other wide aperture lenses, the narrow depth of field is a challenge and you need to be extra careful with your focus. That's because when opened at its widest f/1.4, the depth of field is so narrow that anything further away from the main focal point will be soft.
We prefer the wider Panasonic 14mm f/2.5 pancake lens as a more general purpose lens but it doesn't do portraits as beautifully as the 25mm f/1.4, not just because of the narrower depth of field, but also because the 25mm lens produces a 'flatter image' with less perspective distortion.