While both handsets do seem to look rather similar to the smartphone that came before them, the Xperia Z3, there has been a fair number of changes and improvements introduced by Sony – which means that you, the end user, gets to enjoy whatever subtle differences there are. It looks like the battery itself is not too difficult to take out, which is similar to the rest of the majority of the internal components, and this does have the implication of the handset being easier to repair as opposed to other smartphones. You will require a Phillips screwdriver to get things going however.
Still, it is always better to let a professional look at your device if something goes wrong, unless you are really sure of what you’re doing.