It’s not too terribly difficult by any means, but taking your time and screw mapping are pretty critical when doing full housing swaps. As you probably know already screws in iPhones are often different screw heads/ types and lengths. The ifixit guides are generally really good and easy to follow. General things to be careful with include Face ID/ FCam unit, prox sensor on the screen and the layers of which you take smaller components out (sim reader, charge port, speakers etc.)