I use this App every day, and at the start it helped sync all my calenders from different programs. It is easy to use and set up new calenders. Nothing bad to say about the App itself. I also noticed they come out with updates very regularly, fixing any bugs and always adding to the performance side of their app. If you have the money to spend (50$) when I bought it for my Mac, and use calenders everyday - then get it. However if you are not religously using calenders to keep all your appointments in line - then just use the basic calander app on the Mac computer.
MatchNaller about Fantastical - Calendar, v2.0.7