I found this map to be lacking many things needed to become a good invasion map. Although the player is tested during the mission, it becomes rather hopeless the longer you survive.
The playability rating also covers the map title. Rat Roast is not the name of the mission onve you have unzipped the file. I can see it being something similar possibly but you will need to take note of the map title before you search for it in your maps folder. The wave after wave of large attacks midway through this mission with little if any time allowed to rebuild your defenses makes this map extreme and not enjoyable. A good Invasion map does not have to have countless impossible invasions to make it a challenge. A good balance between invasions and a struggle to rebuild will always rate much higher.
The balance of this map also suffers for the same reasons. During two back to back large invasions you have fires break out within the castle. This makes for a real pain and again timing is the key to enjoyment.
Although the map settings and playability were not ranked high, I found the design of the map had a good deal of merit. Very nice looking castle and good area around it. Both map design and creativity got bonus marks.
The story was pretty much non existant and had little to do with the game play.