Manor is one of the standard maps that came with the original Killing Floor beta version.
The layout is mid range and close quarters. The best weapons to use are as always dependent on your teams playstyle.
For example: if you plan to stay most of the time inside of the Manor itself or in the basement, you should definitly get a shotgun or a strong melee weapon. But if you plan to stay at the area in front of the manor and the boat house you should take a medium ranged rifle or submachineguns.
Explosive and Long ranged weapons will not be very helpful, except for possibly in the swamp or inside of the cave, because of the explosive blast or clearer view.
The atmosphere of the map is, especially inside of the manor, really creepy and becomes even more intense if you travel down the stairs into the basement. Outside it seems rather lonely and cold with a mix of fog and rain.