well, the stones may, or may not, actually need sealed. It depends how they were made. If they are natural the yes, definitely, they should be sealed. If they are ceramic or porcelain tiles that look like stone then no, only the grout. Actually, same thing with the walls. That looks like porcelain or ceramic tile, BUT, if its slate or granite or similar it should be sealed too. The border inlay may have some stone products that may need to be sealed too.
BTW - I think the shower looks great! Maybe a clear glass door would finish it off nicely, allow lots of light in, and allow you to admire the tile job (or your spouse) from the room