Seen it and, I'm sorry it's just too plain. Try varying textures, work on you differential shading and but a bit more detail to the geometry and it might be at least 50% better IMO.

The flow is going to have monumental problems. There was a dead end of note in the bottom left; a large portion of the map is just one long corridor. Also, the texturing is very bland, and instead of putting a liquid texture to the floor, I think it might be a little more seeming to actually give them a liquid. Also, the map seems very flat, and too cramped. Open things up, and try to limit your hallways.