Often mentioned as an essential expansion for the base game. I agree. The new Dunwich locations are pretty neat, the Dunwich Horror (if it shows up) is a tough nut to crack and very thematic and the additions to the base game (new investigators, etc and especially the injury/madness deck) are excellent.
An interesting expansion that adds to the game on all levels. The different strategies now feel somewhat more balanced and the game rounds more flexible. The new homeworlds do not win a prize for me, though.
A generally very useful expansion of the game but I notice over and over again that TI3 can never guarantee to deliver. Much depends on external factors to make this game an awesome experience. The few time where this happens, however, are games to remember. I strongly suggest to play with a preset map, the aggressive goals and all goals uncovered from the beginning.