I received my expansion last week or so but do not see much talk about the expansion lately. I found that it ramp the difficulty. Mythos cards and Agreements (worse then dark pacts) can be devastating. I played using the edition's cards on top of decks, its investigators and fill out mythos with them. With the mysteries we got, we have only 12 rounds to do two mysteries and we get penalized for every four rounds we take. Mysteries are a lot of work, and one bad rumour just can throw ratchet into everything.
Due to game running longer due to being new cards, we yet to finish the game but the end of the two games we had it did not look pretty when we left the table.