Great addition to the game!  The expansion is actually two expansions in one and allows for 6 players.  I feel that in order to play both expansions at the same time 5 or 6 is the number to play with or the buildings don't really come into play.  The new spaces are quite powerful but do come with some drawbacks to discourage players from using them exclusively.  I lost 81 points the first time I played this expansion, be warned.