Call of Cthulhu's written adventures are some of the best on the market. But The Haunting isn't one of them. It's a very straightforward scenario, but, as written, little of the investigation during the scenario actually helps the investigators rid themselves of the menace at the final location. Thankfully, Alone against the Flames is an excellent adventure to introduce you to the mythos, as well as give you ideas how to run a CoC adventure.
As for the ruleset, CoC's skill check system is easy to pick up for roleplayers familiar with other roleplaying games. However, the way most CoC adventures are designed, investigators have to follow a trail of clues -- and if they fail their skill checks, the game master has to find some way to put them on track again. 7th edition added a "push" mechanic which allows a player to attempt another skill check, which helps address this problem, but we now play a homemade rules-light system that takes care of this.
Finally, of course, these rules are free, and you only need to print about ten pages for each player so they have their own set of rules. No more "passing around the rulebook". I'm not sure what the best free adventure is, however.
SPOILER: I highly recommend removing the glowing symbols at the Church, since they're not even explained why they're there. You may wish to modify the tome found at the Church to contain a spell that will help the party at the climax.
[4 of 5 Stars!]