Thimios, the room is gorgeous!
It will, however, definitely need some acoustic treatment. This can be done without destroying the beautiful look you have accomplished. A carpet between the speakers has already been suggested and is a great idea. "Art panel" type absorption panels will look like paintings, but help cure reflections. I think modern, abstract prints would look fabulous. You might be able to get away with a stand mounted panel along the glass wall. One thing for sure, with a room that pretty, you want to audition enough speakers to make a great choice.
