The other day I stopped by my local camera shop to purchase a step up adapter and show off my new Batis 25mm f2 (they don't carry Zeiss lenses) and saw that they had the new $249 Sony FE 50 f1.8 in stock. They always let me try out lenses if I ask, so I thought it would be a good opportunity to give it a brief, albeit very brief, test. Prior to this lenses release the only native autofocus 50ish lens was the Sony/Zeiss 55mm f1.8 which costs nearly $1000. Then there is the Zeiss Loxia which is manual focus only and costs nearly $1000. Adapters allow for the use of many other lenses, which have been a popular option for the FE system. My most popular blog article is a review of the Voigtlander 40mm f1.4 on the A7II due to demand for an affordable standard focal length lens on A7 cameras.
Both Shots were taken on the A7II, ISO 800, f2, and 1/100 (the one with the Loxia pictured was taken with the Sony and vice versa). This is not meant to be a technical comparison, but rather a summary of my, again brief, experience.
I own the Loxia 50mm and will not be trading it in for the new Sony option, but if this lens had been out when I first got my Sony I would definitely own it. Considering the price, the Sony performs impressively. The Loxia is sharper and produces a slightly more pleasing image, but the differences are slight. For most usages the Sony's autofocus will help you get the shot and negate the Zeiss lenses slight image quality advantages.
In summary the Sony is cheaper, has autofocus, has good image quality, and is light weight. The Loxia has incredible build quality with a weather sealing gasket at the mount, metal lens hood, actual mechanical focus ring vs focus by wire, Zeiss T* coatings, and slightly better image quality. For most hobbyists the Sony FE 50mm will be the right choice, more serious photographers may be interested in either the Loxia or the FE 55