Before, the walls were flesh-coloured, there was a really grotty cream carpet, the ceiling was covered in polystyrene tiles and there was a cupboard built in to the space above the stairs, which meant that with just one single bed there was next to no floorspace.
Now, it looks like this:
The top bunk
The bottom bunk
The cupboard has been ripped out and a stud wall put up in its place and floorboards put over the stairwell covering. The ceiling has been stripped and replastered. The bare area around the cupboard has been filled with woodchip wallpaper and the whole thing has been painted with four coats of magnolia. Underlay and a red carpet have been fitted. A custom-built built-in bunk bed has been constructed from scratch, to fit around the radiator and the window/curtains. Two ethernet ports have been fitted underneath the bed, which is enclosed as a lockable storage space for toys and what have you.
There is now the space of a kingsize bed for floorspace in that room and we can get on with putting in a chest of drawers, a TV bracket, two computers, etc.
The whole thing has taken many weekends of work over the course of several months; many thanks to all the people who have helped with this. Now it just needs a few finishing touches, protecting the wood with either stain or varnish, the door putting back on and some curtains :)
If the rest of my house comes out this well I will be dead chuffed :)