I would love to own a Canon 50mm 1.4. It is still more than triple the price of the 50mm 1.8. The question is: Is it worth it?
The 50 mm 1.4 is good for taking picture where there is less light, for example taking a picture in the night near a street with few road lamps and some cars driving by. It is also of course good for taking portraits. Compared to 50 mm 1.8 this lens takes brighter pictures and also sometimes it can be felt to be taking sharper pictures as well.