Ok, so I know this is a bedroom but it's a great use of space for a small room. I particularly like the use of the dead space behind the ladder for shelving. It could also be a cool idea for a kids play room.
Awesome Loft Beds--Since you won't have a window on the one end of your upstairs, this could be a fun idea for the kids area. Not necessarily a bed, but a 'loft' on top of a 'hide-out' area---or something. The bookshelf stairs are a neat idea too.
25 Amazing Beds That Are Almost Too Amazing To Sleep In
A small space idea, like a tree house in your room. Utilize all space with shelf stairs up to the bed box. Get a closet too and all of it up off the floor space. Great for a boys room. Put a BB Net on the bed and voila! they can play indoors.