CameraLabs tested this rather unique lens and concludes:
Laowa’s 25mm f2.8 2.5-5x Ultra Macro is a very special macro lens: Its major attraction is being able to achieve up to 5x magnification (at working distances around 4cm/1.6in) without any additional gear. But – like other lenses achieving 5x magnification – it has only manual focus and cannot focus to infinity. The lens produces sharp images with very little field-curvature across the full frame, copes well in contra-light situations, has pretty nice Bokeh, and comes at an affordable price. This all clearly earns the 25mm f2.8 2.5-5x Ultra Macro a recommendation. Just make sure to use a good focus rail and focus stacking software.