Perhaps the best solution for affordable wide-angle photos in MFT, considering that the cheapest rectilinear lens starts at 600€ (almost double the price). The lens is sharp enough to remove inherent distortion without the corners becoming blurry, and it also doesn't easily produce chromatic aberrations or lens flare. Since it doesn't have autofocus, it requires attention to focus, as the focus ring can easily turn unintentionally and blur the photo. Also, be careful with fingers, as it has a 180° field of view from corner to corner and they may appear in the corners of the frame.

The only fisheye lens I have worked with that does not produce chromatic aberrations...
Extremely sharp even at f/3.5 and so small that it fits everywhere.