Well, the expansions cost almost as much as the game. It adds another board, about a third of the side, more monsters, more cards, and more rules. The Dunwich board is cool, but it doesn't always come into play during a regular game. Unleashing the Dunwich Horror, which roams around the board, can happen but it hasn't happened to us yet. It also makes the game more difficult, since there are more possible locations for gates to open. Plus, the new cards which feature "gate bursts" that can destroy elder sign-sealed gates has screwed us several times.
It's fun. I want to get the other expansions, but like I said, they cost not a small amount of money.
I have a decent collection of games (more than 100), but only a few expansions. When I need to choose between buying expansions or completely different games, I usually end up buying completely different games.
I bought one of my nephews LAST NIGHT ON EARTH and the GROWING HUNGER expansion for Christmas. I played it with him and his brother last week - they were the humans I and was the zombies. I was in control for most of the game, but they beat me on their very last move.