Full review link
All the following below is taken from Robin Wong’s article linked above.
50mm F1.8 vs F1.4 Perception Argument
“If you come from Canon and Nikon background (both are great brands, I am not implying anything negative here, so please spare me some torture in the forums) you will surely be aware of the existence and more importantly, the stark difference between two main versions of the 50mm prime lenses, namely 50mm F1.8 and 50mm F1.4. The 50mm F1.4 is universally known and agreed to be the superior lens in comparison to the 50mm F1.8 lens. This is true not just because of that 2/3 stop of EV faster, but also in terms of optical quality and performance of the 50mm F1.4 being better, delivering unquestionably sharper output with better technical flaw controls (such as less distortion, better corner sharpness, less chromatic aberration, smoother bokeh, etc). There is no debate that 50mm F1.4 is surely better than 50mm F1.8, and this fact is further emphasized in the huge difference in pricing, with the 50mm F1.4 costing about 3-4 times more expensive than the 50mm F1.8. The truth and reality for those familiar with Canon and Nikon lens system are much simpler and straightforward. However, this does not apply to Panasonic 25mm F1.4 vs Olympus 25mm F1.8 lenses at all.”
Panasonic at f/1.4 Olympus at f/1.8