The room was basically as described - for Mykonos, it was good value. In reality it was essentially a converted linen cupboard within the Hotel Matina. You're a little bit like Harry Potter in the cupboard under the stairs, with more space to move around. To illustrate, the room is flanked by two of the hotel's rooms, and its door is just over half the size.
The bathroom is a cupboard within a cupboard, with enough room for a toilet, a small sink, and a hand held shower fixture - you'd be unable to stretch your arms out and spin around in the space. There are stairs up to the room, and from the room into the bathroom another three steps. You need a certain level of agility to navigate the space.
In all, it's perfect for a solo traveller who wants to be smack bang in the middle of Mykonos town with the basic comforts of a private bathroom and air conditioning. It's the closest thing you could get to staying in a decent hotel without paying the obscene Mykonos rates.