A 50mm focal length is a 50mm focal length regardless of the lens model being used and the focal length must be right for your application for this lens to be a good choice for you, regardless of how impressive this lens is. Fifty mm is a very natural focal length as it approximates how we perceive a scene with our own eyes (at least in field of view and perspective terms). The 50mm focal length is known as a “normal” focal length and for good reason as the pictures created using it look very normal/natural to the photographer and viewer. The popularity of 50mm lenses has been long-lasting (my first SLR came with one) and the volume of 50mm lens models available to choose from reflects photographers' interest in this focal length and those not-relevantly-different close-to-50mm variants. Based on this demand alone, the 50mm focal length is obviously a useful one.
Fifty mm lenses frequently find themselves being used in fashion, portraiture, weddings, documentary, lifestyle, sports, architecture, landscape and general studio photography applications. A number of the good applications for this lens include people as subjects. A 50mm lens used on a full frame body is modestly too wide angle for tightly framed head shot portraits (for my taste), but 50mm is very nice for less-tightly-framed head and shoulders, partial body and full body portraits.