This map is based on the 7th Guest and the 11th Hour. It has quite an atmosphere. Unfortunately there really is no flow to the level, or even much playability in any sort of multi-player game. Currently the level is pretty much a straight shot, with very few linking corridors and many dead end rooms. The author states in the readme "In its current state, the mansion is far from its sheer size and volume". This looks like the base of a very interesting level to say the least, Quake 3 doesn't have many haunted house type maps, as a matter of fact I can't think of one. By far the best aspect of this map currently is the sounds.
You're probably better off not getting this map now, but keep your eye out for its completion it may be something great.