Its basically a legal advert virus that relies on one person to sign up and invite all their phone/facebook contacts (which it collects of the names,numbers,emails,messages of) and what do you get in return? Aside from the multitude of direct and spam marketing likely heading your way when your data is sold to the app's 3rd party advertisers you get a tool that Facebook already offers you?
The types of personal information collected in conjunction with the activities listed above will vary depending on the activity. The requested information may include: (i) your name, (ii) mailing address, (iii) telephone number, (iv) email address, and, for those purchasing products or services online, credit card and billing information; and (v) information about the identity of your friends.
For some activities, MyCalendar may also ask you to provide other non-personal information such as: (i) your age or date of birth; (ii) your gender; (iii) your game and platform preferences; (iv) information about the hardware you may own and/or games you may have recently purchased; (v) your interests, websites, friend information and fan pages; and, (vi) other service-related information (collectively referred to as "demographic information"). If demographic information is collected for an activity that also requires personal information, MyCalendar may combine your demographic information with your personal information. Before providing the Service any email addresses or phone numbers of your friends, you should obtain their consent.