There's only so much that can be suggested without playing on the map itself. Like skipperlink said, the area looks a bit open and flat, but aside from that, it's hard to judge without jumping in-game and seeing it, especially since we have only 1 screenshot and no idea what the surrounding areas look like. In TF2, each playspace interacts with adjoining playspaces, and one area may work really well or really poorly depending on the space around it. One other tip that I'll offer though, don't make the room symmetrical, at least not out of laziness; symmetrical rooms generally look lazy (except for at the mid area of a symmetrical map, which you have admitted this is not). Making the room asymmetrical allows you to diversify the gameplay and make each route in and out have its own advantages and disadvantages.
