I would get one if you have the room. It is great for shaving legs. Here are a few options: and

I would have one built into the shower. It shouldn't be very deep, perhaps only 10" deep by whatever width seems right, and about 16" high.

I always have an interesting time trying to explain to my clients that this is not space they will be using in their shower anyway, so they might as well make it a useful bench area. And the reason they will not be using it is that when in the shower your arms and elbows are in motion, cleaning your body parts, from your toes to your head. And those arms and elbows need space so you're probably never going to be close enough to the wall to run into that 10" of space that the bench has stolen. Even if your arms are wide spread, your legs, which are down where the bench is, are not!

It is a very nice feature to have. This one in the picture is covered in the same carrera subway tiles as the shower wall.

Even if it's just a triangular perch in a small shower, It's well worth the effort of building it in.