A standard lens on a 35mm camera, the EF 50mm f/1.4 offers excellent light gathering capability and sharpness. (Just not all the way wide wide open, see below.) Use of a gauss type design and two high-refraction lenses, flare at maximum aperture is reduced and astigmatism is negligible. Micro USM motors are fast and quiet, and manual focus is possible with an external ring.
Digital SLR owners looking for an excellent portrait lens need look no further than the EF 50mm. Its f1.4 aperture is superb for low light photography (though the lens is quite soft until you reach f/1.8), and its characteristics are very desirable. It will blur the out of focus background beautifully at wider apertures, allowing the eye to focus on the subject. Read the whole test here