It gives up very little in the way of features in order to achieve its small size. Its image quality is very good and its AF is excellent, but its small viewfinder takes away from the experience a little. Its video and menus aren't as polished as its rivals but its size and battery life make for a powerful combination.
There is a wide range of full-frame mirrorless cameras to choose from, from Nikon, Canon, Panasonic, Sigma, and from Sony as well. We're just not sure the Sony Alpha A7C is one we'd choose. However, the vari-angle screen may be of benefit for vloggers, and those interested in video use. The smaller size may also be useful here, and some people will see this as a benefit.
In many ways it is nearly identical to the Sony a7III. The Sony a7C’s primary focus is on being Compact (it’s right there in the name!), and there have a few sacrifices on that altar [...] In many ways the Sony a7C takes the a7III’s greatest performance strengths and mildly improves on them [...] The sacrifices to compactness are most evident in the handling of the camera.